超連結
维基百科，自由的百科全书
超連結或超链接是指超文本内由一文件連接至另一文件的連結。作用與論文中的參考或注釋類似，以方便讀者隨時參考某一詞彙的定義。
超連結有點像是文學作品中的參考資料列表，它可以結合數據網路(data network)和適當的存取協定來追蹤資料的原始出處，並被儲存、檢視，或顯示為關聯文件中的一部份。
超連結中，最為通行的形式就是在全球資訊網上使用的URL了。瀏覽器通常會用一些特殊的方式來顯示超連結。如不同的文字色彩、大小或樣式。而且，游標移動到超連結上時，也會轉變為手形指示出來。超連結在大部分的瀏覽器裡是顯示為加上底線的藍色字體，當這個連結已經被快取過時，則轉為紫色。當使用者觸發超連結時（例如，用滑鼠左鍵按下超連結），瀏覽器將會顯示出連結的目標。萬一，目標並非HTML檔案時，將依其檔案格式以及瀏覽器自身之plug-in而啟動外部程式以開啟檔案。
Google的搜尋引擎使用PageRank,測量超連結的普及性以決定哪個頁面該被排在前頭。只要某個網頁被越多的頁面連結，他所得到的排序也會提高。It is actually slightly more complicated than that, see PageRank for more information.
[编辑] 法律問題
In some jurisdictions it is or was (for example the Netherlands, see Karin Spaink) held that hyperlinks are not merely references or citations, but are devices for copying web pages. Although this principle is generally rejected by digerati[1], the courts that adhere to it see the mere publication of a hyperlink that connects to illegal material to be an illegal act in itself, regardless of whether referencing illegal material is illegal.
British Telecom sued Prodigy under U.S. Patent No. 4,873,662 claiming that Prodigy infringed its patent on web hyperlinks. However, after costly litigation, a court found for Prodigy, ruling that British Telecom's patent did not actually cover web hyperlinks. [1] Hyperlinks were first described in 1945 in the landmark paper As We May Think, as well in the widely-known project Xanadu starting in the 1960s.
While hyperlinking among pages of Internet content has long been considered an intrinsic feature of the Internet medium, some websites have claimed that linking to them is not allowed without permission, see e.g. [2] and [3] (in Dutch). You do not need to ask permission to link to any page of Wikipedia's.
参见 deep linking。
