出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/10/15 23:52:08」(JST)
| 「WWW」と「ウェブ」はこの項目へ転送されています。その他の用法については「WWW (曖昧さ回避)」、「ウェッブ」をご覧ください。 |
| 世界初のウェブブラウザ（閲覧ソフト）については「WorldWideWeb」を、電子掲示板で用いられるインターネットスラングについては「(笑)」をご覧ください。 |
| インターネット |
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Opte Projectによる、インターネットの一部を通した
ルーティングパスの視覚化 |
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主要項目
アクセス（英語版） - 検閲 - 民主主義
情報格差 - デジタル権利（英語版） |
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ガバナンス
ICANN
Internet Engineering Task Force |
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情報基盤（英語版）
Domain Name System
Hypertext Transfer Protocol |
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サービス
ブログ（ミニブログ）- 電子メール - Fax
ファイル共有 - ファイル転送（英語版） |
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World Wide Web（ワールド ワイド ウェブ、略名：WWW[1]）とは、インターネット上で提供されるハイパーテキストシステム。W3（ダブリュー スリー）[2]あるいは単に Web（ウェブ）[3]とも呼ばれる。インターネットは、異なるプロトコルを用いるコンピュータネットワーク同士を繋いだコンピュータネットワークを指す言葉であり、ウェブはその応用技術のひとつである。また、分散システムでもある。
WWW ではドキュメント（ウェブページ）の記述には主にHTMLやXHTMLといったハイパーテキスト記述言語が使用される。ハイパーテキストとは、ドキュメントに別のドキュメントのURLへの参照を埋め込むことで（これをハイパーリンクと呼ぶ）インターネット上に散在するドキュメント同士を相互に参照可能にするシステムである。
わかりやすい例で言うと、主にマウスによるクリックなどによってページ間を移動することや、別のファイルである画像をドキュメント内に表示させることなどが挙げられる。世界中に張り巡らしたような、つながり方が蜘蛛の巣を連想させることからWorld Wide Web（世界に広がる蜘蛛の巣）と名付けられた。尚、蜘蛛の巣は現実のケーブルの配線を表しているわけではない。HTMLの記述方式は比較的単純なため、急速に広く普及した。
WWW にアクセスするためのソフトウェア（ユーザーエージェント）は WWW クライアントと呼ばれる。そのうち、利用者による閲覧を目的としたものは特にウェブブラウザ（WWW ブラウザ、あるいは単にブラウザ）と呼ばれる。また、WWW サービスを提供するソフトウェアを「WWWサーバソフトウェア」あるいは単に「ウェブサーバ」という。
検索エンジンとウェブディレクトリの出現により、WWW は徐々にその真価を発揮し始める。数学的な理論に基礎付けられたウェブページの順位決定法を実用化することによって、検索エンジンの首座は、一気呵成に確定した。それとは対照的に、すべての分野に亘って個々の事例の集積を要するウェブディレクトリの作成は、継続的で地道な作業によって成し遂げられる辞書の編纂と似ている。前者が数学的手法に依存しているのに対し、後者は分類学的手法によっている点が対照的である。
WWW を参照するにはウェブブラウザなどのソフトウェアを使用する。ウェブブラウザはウェブページなどのドキュメントを WWW サーバから取得し、モニターなどの出力デバイスに表示する。ウェブページに含まれるハイパーリンクをたどることで他の文書を閲覧したり、情報をサーバに送ることで何らかの相互作用をもたらすこともできる。ウェブページはウェブサイトと呼ばれる関連情報を集めた単位でまとめられていることが多い。
「インターネット・サーフィン」という言葉は1992年6月に出版された「ウィルソン・ライブラリー・ビュレッティン」[4]の中のジーン・アーマー・ポリー[5]（司書）の書いた文章から発祥しているという。ポリーは独自にこの言葉を生み出したかもしれないが、1991年から1992年にかけて Usenet で同様の言葉が散見された。更にそれ以前にハッカーのコミュニティで使われていたという証言もある。
英語では、「worldwide」と一語で表記するのが普通だが[要出典]、「World Wide Web」やその略記の「WWW」英語でも普通に使われるようになった[要出典]。最初の頃は、単語を連続して書いて単語の先頭だけを大文字にした 「WorldWideWeb」（インターキャップとかキャメルケースといわれ、プログラマが好む命名規則）とか、ハイフンが入った 「World-Wide Web」（英語の本来の使用法に近い）と表記されることも多かった[要出典]。
ウェブはクライアントサーバモデルに基づくシステムである。
World Wide Web 上のウェブページなどの資源にアクセスするには、まずウェブブラウザにURIを入力するか、ウェブページのリンクをたどればよい。すると、第一段階としてURIのサーバ名を表す部分がドメイン・ネーム・システム (DNS) と呼ばれるインターネットの分散データベースによってIPアドレスに変換される（IPアドレスが直接指定されている場合はこの変換は行われない）。
次に、そのIPアドレスに対応する WWW サーバに対して、URIのスキーム（通信方法などの指定）に従い接続を試みる。プロトコルとしては主にHTTPが使用される。一般的なウェブページでは、ページを構成するHTMLドキュメントや画像ファイルが要求され、即座に要求元に転送される。
ウェブブラウザは、受け取ったHTMLファイルやCSSファイルにしたがってレンダリングし、画像をはめ込み、リンクをはめ込むなどの仕事を行う。これによってユーザーが見ている画面上の「ページ」が生み出される。
多くのウェブページは他の関連するページとのハイパーリンクを含んでいる。それは例えばダウンロードのページだったり、ソース文書だったり、他の定義だったり、ウェブ上の何かの資源だったりする。このハイパーリンクによって情報の網（英語: web）が形成される。これによって World Wide Web が構成されているのである。
ウェブの根底にある考え方は1980年にティム・バーナーズ＝リーがロバート・カイリューと構築したENQUIRE （エンクワイア）に遡ることができる。その名称は「エンクワイア・ウィズィン・アポン・エブリシング」[6]というビクトリア朝時代の日常生活のハウツー本に由来していて、バーナーズ＝リーが幼少のころを思い出して付けたものである。それは現在のウェブとは大分違うが、根本的なアイデアの多くを含んでおり、更にはバーナーズ＝リーの WWW 後のプロジェクトである セマンティック・ウェブ の考え方をも含んでいた。しかし、ENQUIRE は一般に公表されるまでには至らなかった。
1989年3月、欧州原子核研究機構 (CERN) のティム・バーナーズ＝リーは「Information Management: A Proposal」（情報管理: 提案）を執筆し、ENQUIRE を参照しつつさらに進んだ情報管理システムを描いた[7]。彼は1990年11月12日、World Wide Web をより具体化した提案書「WorldWideWeb: Proposal for a HyperText Project」[8]を発表した。実装は1990年11月13日から開始され、バーナーズ＝リーは最初のウェブページ[9]を NeXTワークステーション上に置いた。
その年のクリスマス休暇の間に、バーナーズ＝リーは WWW に必要な全ツールを構築した[10]。世界初のウェブブラウザ（ウェブエディタでもある）と世界初のWWWサーバである。
1991年8月6日、彼は World Wide Web プロジェクトに関する簡単な要約[11]をalt.hypertextニュースグループに投稿した。この日がWWWがインターネット上で利用可能なサービスとしてデビューした日となる。
ハイパーテキストの概念は1960年代にまで遡ることができる。テッド・ネルソンのザナドゥ計画、ダグラス・エンゲルバートの oN-Line System (NLS) などである。ネルソンもエンゲルバートも、ヴァネヴァー・ブッシュのマイクロフィルムベースの夢の装置 memex の影響を受けたものであり、memex は1945年の論文「As We May Think」[12]で描かれている。
バーナーズ＝リーのブレイクスルーはハイパーテキストとインターネットを結合したことである。彼は著書「Weaving The Web」の中で、このふたつの技術の結合は双方の技術コミュニティの協力によって成立することを強調しているが、誰もこの提案を取り上げることはなく、最終的に自分自身でプロジェクトを実行したのである。この過程で彼はURIと呼ばれるグローバルな資源識別子を開発した。
World Wide Web は当時実現していた他のハイパーテキストシステムとはいくつかの点で異なる。
開発当初、WWW は文字情報を扱うだけの比較的単純なものであった（NeXT上で開発されたためOS自身が文字以外を適切に扱うため、WWW は情報を区別しなくてもよかったというのが真相）。しかし1992年、イリノイ大学の米国立スーパーコンピュータ応用研究所 (NCSA) によって、現在のように画像なども扱えるようになった。同校の学生であったマーク・アンドリーセンらは文字だけでなく画像なども扱える革新的なブラウザ Mosaic を開発。そしてこのソフトに改良を加えるために無料でソースコードを公開したため、Mosaic はたちまち普及し、WWW は誰でも手軽に使うことのできる世界的なメディアとなった。
1993年4月30日、CERN は World Wide Web を無料で誰にでも開放することを発表した。
日本最初のホームページを開設したのは、高エネルギー加速器研究機構所属の森田洋平である。
WWW を構成する根本的な標準規格が3つ存在する。
WWW で使われる技術は従来IETFのRFCにより標準化されてきたが、現在は非営利組織である World Wide Web Consortium (W3C) によって標準化が進められている。現在、バーナーズ＝リーはW3Cを指導する立場である。W3Cは上記を含めた様々な標準を開発・保守し、WWW上のコンピュータが様々な形態の情報を格納してやりとりできるよう尽力している。
もうひとつの技術上の大きな発展はサン・マイクロシステムズの Java である。Java によって、小さなプログラム（アプレット）を直接WWWサーバが提供する情報に埋め込むことを可能にした。このアプレットはクライアント側のコンピュータ上で動作し、高速で豊かなユーザインタフェースを可能とした。その後、Java はサーバ側で複雑なコンテンツを自動生成するために広く使われるようになった。
JavaScript はウェブページのために開発された、クライアント側のスクリプト言語である。ネットスケープコミュニケーションズが開発したものである。名前の一部に「Java」を含んではいるが[13]、技術的には Java との関係はほとんどない。文法はC言語に似ている。オブジェクト指向的にコーディングする以外に手続き的にコーディングすることもできる。
DOMと組み合わせることで、JavaScript はその設計者が想像した以上に強力な技術となった。JavaScript の使用はそれまでの静的なHTMLページと区別するためにダイナミックHTML (DHTML) と表現されることが多い。さらに近年は JavaScript を使って、よりインタラクティブなウェブサイトを作ることのできるAjaxという技術も普及している。
今日の WWW は人類の歴史上かつてないスケールで個人間の情報交換を可能とした。時間的空間的な隔たりを越えて、本質的かつ広大な思想や逆にちょっとした個人の姿勢や心情をWWWを通して交換したり発信したりすることができるようになったのである。
感情的な経験、政治的考え方、文化習慣、音楽の風習、ビジネスについての助言、芸術、写真、文学などが、人類史上最も安価にデジタル化されて共有・拡散される。WWW はそれを支える技術と設備の上に成り立っているが、図書館や活字による印刷と違って物理的な形を持たない。そのため WWW（あるいはインターネット）を通した情報伝播は物理的な量に制限されないし、情報をコピーする手間もかからない。またデジタルの利点として、WWW 上の情報は簡単かつ効率的に検索でき、他のどんな通信手段（郵便、電話など）や実地の旅行よりも早く情報を集めることができる。
すなわち WWW は今まで地上に現れた個人の情報交換媒体としては最も広範囲で遠くまで伝達可能なものである。多くのユーザーが世界各地の人々と情報交換し、他の手段では不可能だったことを可能とするだろう。
WWW は社会交流を促して、膨大な知識の集積を育み、個々人の地球規模の理解を深める役に立つと示唆する人もいる。一方、多くの人々を仮想世界に閉じこもらせ、好戦性を増大させ、地球規模の管理・支配体制を生み出すのに使われる可能性も持っているとも言われる。
2001年の研究[14]によれば、ウェブ上の文書は5500億個以上も存在し、その多くは「深層Web」にあるという。
2002年の20億以上のWebページを調査した結果によると[15]、英語のコンテンツが56.4%で最も多く、以下、ドイツ語 (7.7%) 、フランス語 (5.6%) 、日本語 (4.9%) となっていた。これ以降、中国語のページの増加が目立っている。
2005年1月では[16]、75種類の言語でWeb検索を行ってサンプリングし、一般に検索可能なWebは少なくとも115億ページ存在するとの結果を得ている。
2006年2月では[17]、静的なページだけでも150億ページ以上、動的に生成されるページを含めると350億ページ以上が存在するとの推定がある。
英語では「World Wide Web」より「WWW」の略称が一般的。ただし、皮肉なことに、「WWW」の方が「World Wide Web」よりも音節数が多く（下記）、発音するのにかえって時間がかかる。バーナーズ＝リーによれば、他の人はそれを理由に名前を変えるように助言したが、バーナーズ＝リー本人がこの名称に固執したとのことである。
英語圏では、「WWW」は「double-u, double-u, double-u」と発音される（「W」も参照）ため、音節数が6つないし9つになる[18]が、一方の「World Wide Web」は音節数が3つしかない（en:Pronunciation of "www"も参照）。
ニュージーランドでは「doub, doub, doub」と発音されることが多く、これは英語表現中でより簡潔である。
| [ヘルプ] |
| ウィキペディアの姉妹プロジェクトで 「World Wide Web」に関する情報が検索できます。 |
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| ウィクショナリーの辞書項目 | |
| ウィキブックスの教科書や解説書 |
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| ウィキクォートの引用句集 |
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| ウィキソースの原文 |
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| コモンズでメディア |
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| ウィキニュースのニュース |
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| ウィキバーシティの学習支援 |
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以下は、World Wide Web の基本的な3つの標準規格を定義した文書のリストである。
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The World Wide Web (abbreviated WWW or the Web) is an information space where documents and other web resources are identified by Uniform Resource Locators (URLs), interlinked by hypertext links, and can be accessed via the Internet.[1] English scientist Tim Berners-Lee invented the World Wide Web in 1989. He wrote the first web browser computer programme in 1990 while employed at CERN in Switzerland.[2][3][page needed]
The World Wide Web has been central to the development of the Information Age and is the primary tool billions of people use to interact on the Internet.[4][5][6] Web pages are primarily text documents formatted and annotated with Hypertext Markup Language (HTML). In addition to formatted text, web pages may contain images, video, audio, and software components that are rendered in the user's web browser as coherent pages of multimedia content. Embedded hyperlinks permit users to navigate between web pages. Multiple web pages with a common theme, a common domain name, or both, make up a website. Website content can largely be provided by the publisher, or interactive where users contribute content or the content depends upon the user or their actions. Websites may be mostly informative, primarily for entertainment, or largely for commercial, governmental, or non-governmental organisational purposes.
Tim Berners-Lee's vision of a global hyperlinked information system became a possibility by the second half of the 1980s. By 1985, the global Internet began to proliferate in Europe and in the Domain Name System (upon which the Uniform Resource Locator is built) came into being. In 1988 the first direct IP connection between Europe and North America was made and Berners-Lee began to openly discuss the possibility of a web-like system at CERN.[7] In March 1989 Berners-Lee issued a proposal to the management at CERN for a system called "Mesh" that referenced ENQUIRE, a database and software project he had built in 1980, which used the term "web" and described a more elaborate information management system based on links embedded in readable text: "Imagine, then, the references in this document all being associated with the network address of the thing to which they referred, so that while reading this document you could skip to them with a click of the mouse." Such a system, he explained, could be referred to using one of the existing meanings of the word hypertext, a term that he says was coined in the 1950s. There is no reason, the proposal continues, why such hypertext links could not encompass multimedia documents including graphics, speech and video, so that Berners-Lee goes on to use the term hypermedia.[8]
With help from his colleague and fellow hypertext enthusiast Robert Cailliau he published a more formal proposal on 12 November 1990 to build a "Hypertext project" called "WorldWideWeb" (one word) as a "web" of "hypertext documents" to be viewed by "browsers" using a client–server architecture.[9] At this point HTML and HTTP had already been in development for about two months and the first Web server was about a month from completing its first successful test. This proposal estimated that a read-only web would be developed within three months and that it would take six months to achieve "the creation of new links and new material by readers, [so that] authorship becomes universal" as well as "the automatic notification of a reader when new material of interest to him/her has become available." While the read-only goal was met, accessible authorship of web content took longer to mature, with the wiki concept, WebDAV, blogs, Web 2.0 and RSS/Atom.[10]
The proposal was modelled after the SGML reader Dynatext by Electronic Book Technology, a spin-off from the Institute for Research in Information and Scholarship at Brown University. The Dynatext system, licensed by CERN, was a key player in the extension of SGML ISO 8879:1986 to Hypermedia within HyTime, but it was considered too expensive and had an inappropriate licensing policy for use in the general high energy physics community, namely a fee for each document and each document alteration. A NeXT Computer was used by Berners-Lee as the world's first web server and also to write the first web browser, WorldWideWeb, in 1990. By Christmas 1990, Berners-Lee had built all the tools necessary for a working Web:[11] the first web browser (which was a web editor as well) and the first web server. The first web site,[12] which described the project itself, was published on 20 December 1990.[13]
The first web page may be lost, but Paul Jones of UNC-Chapel Hill in North Carolina announced in May 2013 that Berners-Lee gave him what he says is the oldest known web page during a 1991 visit to UNC. Jones stored it on a magneto-optical drive and on his NeXT computer.[14] On 6 August 1991, Berners-Lee published a short summary of the World Wide Web project on the newsgroup alt.hypertext.[15] This date is sometimes confused with the public availability of the first web servers, which had occurred months earlier. As another example of such confusion, several news media reported that the first photo on the Web was published by Berners-Lee in 1992, an image of the CERN house band Les Horribles Cernettes taken by Silvano de Gennaro; Gennaro has disclaimed this story, writing that media were "totally distorting our words for the sake of cheap sensationalism."[16]
The first server outside Europe was installed at the Stanford Linear Accelerator Center (SLAC) in Palo Alto, California, to host the SPIRES-HEP database. Accounts differ substantially as to the date of this event. The World Wide Web Consortium's timeline says December 1992,[17] whereas SLAC itself claims December 1991,[18][19] as does a W3C document titled A Little History of the World Wide Web.[20] The underlying concept of hypertext originated in previous projects from the 1960s, such as the Hypertext Editing System (HES) at Brown University, Ted Nelson's Project Xanadu, and Douglas Engelbart's oN-Line System (NLS). Both Nelson and Engelbart were in turn inspired by Vannevar Bush's microfilm-based memex, which was described in the 1945 essay "As We May Think".[21]
Berners-Lee's breakthrough was to marry hypertext to the Internet. In his book Weaving The Web, he explains that he had repeatedly suggested that a marriage between the two technologies was possible to members of both technical communities, but when no one took up his invitation, he finally assumed the project himself. In the process, he developed three essential technologies:
The World Wide Web had a number of differences from other hypertext systems available at the time. The Web required only unidirectional links rather than bidirectional ones, making it possible for someone to link to another resource without action by the owner of that resource. It also significantly reduced the difficulty of implementing web servers and browsers (in comparison to earlier systems), but in turn presented the chronic problem of link rot. Unlike predecessors such as HyperCard, the World Wide Web was non-proprietary, making it possible to develop servers and clients independently and to add extensions without licensing restrictions. On 30 April 1993, CERN announced that the World Wide Web would be free to anyone, with no fees due.[23] Coming two months after the announcement that the server implementation of the Gopher protocol was no longer free to use, this produced a rapid shift away from Gopher and towards the Web. An early popular web browser was ViolaWWW for Unix and the X Windowing System.
Scholars generally agree that a turning point for the World Wide Web began with the introduction[24] of the Mosaic web browser[25] in 1993, a graphical browser developed by a team at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign (NCSA-UIUC), led by Marc Andreessen. Funding for Mosaic came from the U.S. High-Performance Computing and Communications Initiative and the High Performance Computing and Communication Act of 1991, one of several computing developments initiated by U.S. Senator Al Gore.[26] Prior to the release of Mosaic, graphics were not commonly mixed with text in web pages and the web's popularity was less than older protocols in use over the Internet, such as Gopher and Wide Area Information Servers (WAIS). Mosaic's graphical user interface allowed the Web to become, by far, the most popular Internet protocol. The World Wide Web Consortium (W3C) was founded by Tim Berners-Lee after he left the European Organization for Nuclear Research (CERN) in October 1994. It was founded at the Massachusetts Institute of Technology Laboratory for Computer Science (MIT/LCS) with support from the Defense Advanced Research Projects Agency (DARPA), which had pioneered the Internet; a year later, a second site was founded at INRIA (a French national computer research lab) with support from the European Commission DG InfSo; and in 1996, a third continental site was created in Japan at Keio University. By the end of 1994, the total number of websites was still relatively small, but many notable websites were already active that foreshadowed or inspired today's most popular services.
Connected by the Internet, other websites were created around the world. This motivated international standards development for protocols and formatting. Berners-Lee continued to stay involved in guiding the development of web standards, such as the markup languages to compose web pages and he advocated his vision of a Semantic Web. The World Wide Web enabled the spread of information over the Internet through an easy-to-use and flexible format. It thus played an important role in popularising use of the Internet.[27] Although the two terms are sometimes conflated in popular use, World Wide Web is not synonymous with Internet.[28] The Web is an information space containing hyperlinked documents and other resources, identified by their URIs.[29] It is implemented as both client and server software using Internet protocols such as TCP/IP and HTTP. Berners-Lee was knighted in 2004 by Queen Elizabeth II for "services to the global development of the Internet".[30][31]
The terms Internet and World Wide Web are often used without much distinction. However, the two are not the same. The Internet is a global system of interconnected computer networks. In contrast, the World Wide Web is a global collection of documents and other resources, linked by hyperlinks and URIs. Web resources are usually accessed using HTTP, which is one of many Internet communication protocols.[32]
Viewing a web page on the World Wide Web normally begins either by typing the URL of the page into a web browser, or by following a hyperlink to that page or resource. The web browser then initiates a series of background communication messages to fetch and display the requested page. In the 1990s, using a browser to view web pages—and to move from one web page to another through hyperlinks—came to be known as 'browsing,' 'web surfing' (after channel surfing), or 'navigating the Web'. Early studies of this new behaviour investigated user patterns in using web browsers. One study, for example, found five user patterns: exploratory surfing, window surfing, evolved surfing, bounded navigation and targeted navigation.[33]
The following example demonstrates the functioning of a web browser when accessing a page at the URL http://www.example.org/home.html. The browser resolves the server name of the URL (www.example.org) into an Internet Protocol address using the globally distributed Domain Name System (DNS). This lookup returns an IP address such as 203.0.113.4 or 2001:db8:2e::7334. The browser then requests the resource by sending an HTTP request across the Internet to the computer at that address. It requests service from a specific TCP port number that is well known for the HTTP service, so that the receiving host can distinguish an HTTP request from other network protocols it may be servicing. The HTTP protocol normally uses port number 80. The content of the HTTP request can be as simple as two lines of text:
GET /home.html HTTP/1.1
Host: www.example.org
The computer receiving the HTTP request delivers it to web server software listening for requests on port 80. If the web server can fulfil the request it sends an HTTP response back to the browser indicating success:
HTTP/1.0 200 OK
Content-Type: text/html; charset=UTF-8
followed by the content of the requested page. HyperText Markup Language (HTML) for a basic web page might look like this:
<html>
<head>
<title>Example.org – The World Wide Web</title>
</head>
<body>
<p>The World Wide Web, abbreviated as WWW and commonly known ...</p>
</body>
</html>
The web browser parses the HTML and interprets the markup (<title>, <p> for paragraph, and such) that surrounds the words to format the text on the screen. Many web pages use HTML to reference the URLs of other resources such as images, other embedded media, scripts that affect page behaviour, and Cascading Style Sheets that affect page layout. The browser makes additional HTTP requests to the web server for these other Internet media types. As it receives their content from the web server, the browser progressively renders the page onto the screen as specified by its HTML and these additional resources.
Most web pages contain hyperlinks to other related pages and perhaps to downloadable files, source documents, definitions and other web resources. In the underlying HTML, a hyperlink looks like this: <a href="http://www.example.org/home.html">Example.org Homepage</a>
Such a collection of useful, related resources, interconnected via hypertext links is dubbed a web of information. Publication on the Internet created what Tim Berners-Lee first called the WorldWideWeb (in its original CamelCase, which was subsequently discarded) in November 1990.[9]
The hyperlink structure of the WWW is described by the webgraph: the nodes of the webgraph correspond to the web pages (or URLs) the directed edges between them to the hyperlinks. Over time, many web resources pointed to by hyperlinks disappear, relocate, or are replaced with different content. This makes hyperlinks obsolete, a phenomenon referred to in some circles as link rot, and the hyperlinks affected by it are often called dead links. The ephemeral nature of the Web has prompted many efforts to archive web sites. The Internet Archive, active since 1996, is the best known of such efforts.
JavaScript is a scripting language that was initially developed in 1995 by Brendan Eich, then of Netscape, for use within web pages.[34] The standardised version is ECMAScript.[34] To make web pages more interactive, some web applications also use JavaScript techniques such as Ajax (asynchronous JavaScript and XML). Client-side script is delivered with the page that can make additional HTTP requests to the server, either in response to user actions such as mouse movements or clicks, or based on elapsed time. The server's responses are used to modify the current page rather than creating a new page with each response, so the server needs only to provide limited, incremental information. Multiple Ajax requests can be handled at the same time, and users can interact with the page while data is retrieved. Web pages may also regularly poll the server to check whether new information is available.[35]
Many hostnames used for the World Wide Web begin with www because of the long-standing practice of naming Internet hosts according to the services they provide. The hostname of a web server is often www, in the same way that it may be ftp for an FTP server, and news or nntp for a USENET news server. These host names appear as Domain Name System (DNS) or subdomain names, as in www.example.com. The use of www is not required by any technical or policy standard and many web sites do not use it; indeed, the first ever web server was called nxoc01.cern.ch.[36] According to Paolo Palazzi,[37] who worked at CERN along with Tim Berners-Lee, the popular use of www as subdomain was accidental; the World Wide Web project page was intended to be published at www.cern.ch while info.cern.ch was intended to be the CERN home page, however the DNS records were never switched, and the practice of prepending www to an institution's website domain name was subsequently copied. Many established websites still use the prefix, or they employ other subdomain names such as www2, secure or en for special purposes. Many such web servers are set up so that both the main domain name (e.g., example.com) and the www subdomain (e.g., www.example.com) refer to the same site; others require one form or the other, or they may map to different web sites. The use of a subdomain name is useful for load balancing incoming web traffic by creating a CNAME record that points to a cluster of web servers. Since, currently, only a subdomain can be used in a CNAME, the same result cannot be achieved by using the bare domain root.[citation needed]
When a user submits an incomplete domain name to a web browser in its address bar input field, some web browsers automatically try adding the prefix "www" to the beginning of it and possibly ".com", ".org" and ".net" at the end, depending on what might be missing. For example, entering 'microsoft' may be transformed to http://www.microsoft.com/ and 'openoffice' to http://www.openoffice.org. This feature started appearing in early versions of Mozilla Firefox, when it still had the working title 'Firebird' in early 2003, from an earlier practice in browsers such as Lynx.[38] It is reported that Microsoft was granted a US patent for the same idea in 2008, but only for mobile devices.[39]
In English, www is usually read as double-u double-u double-u.[40] Some users pronounce it dub-dub-dub, particularly in New Zealand. Stephen Fry, in his "Podgrammes" series of podcasts, pronounces it wuh wuh wuh.[citation needed] The English writer Douglas Adams once quipped in The Independent on Sunday (1999): "The World Wide Web is the only thing I know of whose shortened form takes three times longer to say than what it's short for".[41] In Mandarin Chinese, World Wide Web is commonly translated via a phono-semantic matching to wàn wéi wǎng (万维网), which satisfies www and literally means "myriad dimensional net",[42] a translation that reflects the design concept and proliferation of the World Wide Web. Tim Berners-Lee's web-space states that World Wide Web is officially spelled as three separate words, each capitalised, with no intervening hyphens.[43] Use of the www prefix is declining as Web 2.0 web applications seek to brand their domain names and make them easily pronounceable.[44] As the mobile web grows in popularity, services like Gmail.com, Outlook.com, MySpace.com, Facebook.com and Twitter.com are most often mentioned without adding "www." (or, indeed, ".com") to the domain.
The scheme specifiers http:// and https:// at the start of a web URI refer to Hypertext Transfer Protocol or HTTP Secure, respectively. They specify the communication protocol to use for the request and response. The HTTP protocol is fundamental to the operation of the World Wide Web, and the added encryption layer in HTTPS is essential when browsers send or retrieve confidential data, such as passwords or banking information. Web browsers usually automatically prepend http:// to user-entered URIs, if omitted.
For criminals, the Web has become the preferred way to spread malware and engage in a range of cybercrimes, including identity theft, fraud, espionage and intelligence gathering.[45] Web-based vulnerabilities now outnumber traditional computer security concerns,[46][47] and as measured by Google, about one in ten web pages may contain malicious code.[48] Most web-based attacks take place on legitimate websites, and most, as measured by Sophos, are hosted in the United States, China and Russia.[49] The most common of all malware threats is SQL injection attacks against websites.[50] Through HTML and URIs, the Web was vulnerable to attacks like cross-site scripting (XSS) that came with the introduction of JavaScript[51] and were exacerbated to some degree by Web 2.0 and Ajax web design that favours the use of scripts.[52] Today by one estimate, 70% of all websites are open to XSS attacks on their users.[53] Phishing is another common threat to the Web. "SA, the Security Division of EMC, today announced the findings of its January 2013 Fraud Report, estimating the global losses from phishing at $1.5 Billion in 2012".[54] Two of the well-known phishing methods are Covert Redirect and Open Redirect.
Proposed solutions vary. Large security companies like McAfee already design governance and compliance suites to meet post-9/11 regulations,[55] and some, like Finjan have recommended active real-time inspection of programming code and all content regardless of its source.[45] Some have argued that for enterprises to see Web security as a business opportunity rather than a cost centre,[56] while others call for "ubiquitous, always-on digital rights management" enforced in the infrastructure to replace the hundreds of companies that secure data and networks.[57] Jonathan Zittrain has said users sharing responsibility for computing safety is far preferable to locking down the Internet.[58]
Every time a client requests a web page, the server can identify the request's IP address and usually logs it. Also, unless set not to do so, most web browsers record requested web pages in a viewable history feature, and usually cache much of the content locally. Unless the server-browser communication uses HTTPS encryption, web requests and responses travel in plain text across the Internet and can be viewed, recorded, and cached by intermediate systems. When a web page asks for, and the user supplies, personally identifiable information—such as their real name, address, e-mail address, etc.—web-based entities can associate current web traffic with that individual. If the website uses HTTP cookies, username and password authentication, or other tracking techniques, it can relate other web visits, before and after, to the identifiable information provided. In this way it is possible for a web-based organisation to develop and build a profile of the individual people who use its site or sites. It may be able to build a record for an individual that includes information about their leisure activities, their shopping interests, their profession, and other aspects of their demographic profile. These profiles are obviously of potential interest to marketeers, advertisers and others. Depending on the website's terms and conditions and the local laws that apply information from these profiles may be sold, shared, or passed to other organisations without the user being informed. For many ordinary people, this means little more than some unexpected e-mails in their in-box, or some uncannily relevant advertising on a future web page. For others, it can mean that time spent indulging an unusual interest can result in a deluge of further targeted marketing that may be unwelcome. Law enforcement, counter terrorism and espionage agencies can also identify, target and track individuals based on their interests or proclivities on the Web.
Social networking sites try to get users to use their real names, interests, and locations, rather than pseudonyms. These website's leaders believe this makes the social networking experience more engaging for users. On the other hand, uploaded photographs or unguarded statements can be identified to an individual, who may regret this exposure. Employers, schools, parents, and other relatives may be influenced by aspects of social networking profiles, such as text posts or digital photos, that the posting individual did not intend for these audiences. On-line bullies may make use of personal information to harass or stalk users. Modern social networking websites allow fine grained control of the privacy settings for each individual posting, but these can be complex and not easy to find or use, especially for beginners.[59] Photographs and videos posted onto websites have caused particular problems, as they can add a person's face to an on-line profile. With modern and potential facial recognition technology, it may then be possible to relate that face with other, previously anonymous, images, events and scenarios that have been imaged elsewhere. Because of image caching, mirroring and copying, it is difficult to remove an image from the World Wide Web.
Many formal standards and other technical specifications and software define the operation of different aspects of the World Wide Web, the Internet, and computer information exchange. Many of the documents are the work of the World Wide Web Consortium (W3C), headed by Berners-Lee, but some are produced by the Internet Engineering Task Force (IETF) and other organisations.
Usually, when web standards are discussed, the following publications are seen as foundational:
Additional publications provide definitions of other essential technologies for the World Wide Web, including, but not limited to, the following:
There are methods for accessing the Web in alternative mediums and formats to facilitate use by individuals with disabilities. These disabilities may be visual, auditory, physical, speech-related, cognitive, neurological, or some combination. Accessibility features also help people with temporary disabilities, like a broken arm, or ageing users as their abilities change.[60] The Web receives information as well as providing information and interacting with society. The World Wide Web Consortium claims that it is essential that the Web be accessible, so it can provide equal access and equal opportunity to people with disabilities.[61] Tim Berners-Lee once noted, "The power of the Web is in its universality. Access by everyone regardless of disability is an essential aspect."[60] Many countries regulate web accessibility as a requirement for websites.[62] International cooperation in the W3C Web Accessibility Initiative led to simple guidelines that web content authors as well as software developers can use to make the Web accessible to persons who may or may not be using assistive technology.[60][63]
The W3C Internationalisation Activity assures that web technology works in all languages, scripts, and cultures.[64] Beginning in 2004 or 2005, Unicode gained ground and eventually in December 2007 surpassed both ASCII and Western European as the Web's most frequently used character encoding.[65] Originally RFC 3986 allowed resources to be identified by URI in a subset of US-ASCII. RFC 3987 allows more characters—any character in the Universal Character Set—and now a resource can be identified by IRI in any language.[66]
Between 2005 and 2010, the number of web users doubled, and was expected to surpass two billion in 2010.[67] Early studies in 1998 and 1999 estimating the size of the Web using capture/recapture methods showed that much of the web was not indexed by search engines and the Web was much larger than expected.[68][69] According to a 2001 study, there was a massive number, over 550 billion, of documents on the Web, mostly in the invisible Web, or Deep Web.[70] A 2002 survey of 2,024 million web pages[71] determined that by far the most web content was in the English language: 56.4%; next were pages in German (7.7%), French (5.6%), and Japanese (4.9%). A more recent study, which used web searches in 75 different languages to sample the Web, determined that there were over 11.5 billion web pages in the publicly indexable web as of the end of January 2005.[72] As of March 2009[update], the indexable web contains at least 25.21 billion pages.[73] On 25 July 2008, Google software engineers Jesse Alpert and Nissan Hajaj announced that Google Search had discovered one trillion unique URLs.[74] As of May 2009[update], over 109.5 million domains operated.[75][not in citation given] Of these, 74% were commercial or other domains operating in the generic top-level domain com.[75] Statistics measuring a website's popularity, such as the Alexa Internet rankings, are usually based either on the number of page views or on associated server "hits" (file requests) that it receives.
Frustration over congestion issues in the Internet infrastructure and the high latency that results in slow browsing, "freezing" of Web pages, and slow loading of websites has led to a pejorative name for the World Wide Web: the World Wide Wait.[76] Speeding up the Internet is an ongoing discussion over the use of peering and QoS technologies. Other solutions to reduce the congestion can be found at W3C.[77] Guidelines for web response times are:[78]
A web cache is a server computer located either on the public Internet, or within an enterprise that stores recently accessed web pages to improve response time for users when the same content is requested within a certain time after the original request. Most web browsers also implement a browser cache for recently obtained data, usually on the local disk drive. HTTP requests by a browser may ask only for data that has changed since the last access. Web pages and resources may contain expiration information to control caching to secure sensitive data, such as in online banking, or to facilitate frequently updated sites, such as news media. Even sites with highly dynamic content may permit basic resources to be refreshed only occasionally. Web site designers find it worthwhile to collate resources such as CSS data and JavaScript into a few site-wide files so that they can be cached efficiently. Enterprise firewalls often cache Web resources requested by one user for the benefit of many users. Some search engines store cached content of frequently accessed websites.
He wove the World Wide Web and created a mass medium for the 21st century. The World Wide Web is Berners-Lee's alone. He designed it. He loosed it on the world. And he more than anyone else has fought to keep it open, nonproprietary and free.
With recent phenomena like blogs and wikis, the Web is beginning to develop the kind of collaborative nature that its inventor envisaged from the start.
If you read well our website, it says that it was, to our knowledge, the 'first photo of a band'. Dozens of media are totally distorting our words for the sake of cheap sensationalism. Nobody knows which was the first photo on the Web.
|url= (help)|url= (help)| Wikimedia Commons has media related to W3C. |
| Wikibooks has a book on the topic of: Nets, Webs and the Information Infrastructure |
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| リンク元 | 「ウェブ」「ウェッブ」「ワールドワイドウェブ」「www」 |
| 関連記事 | 「web」「wide」「W」「world」 |