The "W3C "Recommendation called "XLink describes hyperlinks that offer a far greater degree of functionality than those offered in HTML. These extended links can be multidirectional, linking from, within, and between XML documents. It also describes simple links, which are unidirectional and therefore offer no more functionality than hyperlinks in HTML.
Hyperlinks are used in the "Gopher protocol, "text editors, "PDF documents, help systems such as "Windows Help, "word processing "documents, "spreadsheets, "Apple's "HyperCard and many other places.
Hyperlinks are being implemented in various 3D "virtual world networks, including those which utilize the "OpenSimulator and "Open Cobalt platforms.
While "wikis may use HTML-type hyperlinks, the use of "wiki markup, a set of "lightweight markup languages specifically for wikis, provides simplified syntax for linking pages within wiki environments—in other words, for creating wikilinks.
The syntax and appearance of wikilinks may vary. "Ward Cunningham's original "wiki software, the "WikiWikiWeb used "CamelCase for this purpose. CamelCase was also used in the early version of "Wikipedia and is still used in some wikis, such as "TiddlyWiki, "Trac, and "PMWiki. A common markup syntax is the use of double square brackets around the term to be wikilinked. For example, the input "[[zebras]]" will be converted by wiki software using this markup syntax to a link to a "zebras article. Hyperlinks used in wikis are commonly classified as follows:
- Internal wikilinks or intrawiki links lead to pages within the same wiki website.
- Interwiki links are simplified markup hyperlinks that lead to pages of other wikis that are associated with the first.
- External links lead to other webpages (those not covered in the above two cases, wiki or not wiki).
Wikilinks are visibly distinct from other text, and if an internal wikilink leads to a page that does not yet exist, it usually has a different specific visual appearance. For example, in Wikipedia wikilinks are displayed in blue, except those which link to pages which do not yet exist, which are instead shown in red. Another possibility for linking is to display a highlighted clickable question mark after the wikilinked term.
A link from one domain to another is said to be outbound from its source anchor and "inbound to its target.
The most common destination anchor is a "URL used in the "World Wide Web. This can refer to a document, e.g. a "webpage, or other resource, or to a position in a webpage. The latter is achieved by means of an "HTML element with a "name" or "id" attribute at that position of the HTML document. The URL of the position is the URL of the webpage with a "fragment identifier — "#id attribute" — appended.
When linking to PDF documents from an HTML page the "id attribute" can be replaced with syntax that references a page number or another element of the PDF, for example, "#page=386".
Link behavior in web browsers
A "web browser usually displays a hyperlink in some distinguishing way, e.g. in a different "color, "font or "style. The behavior and style of links can be specified using the "Cascading Style Sheets (CSS) language.
In a graphical user interface, the appearance of a "mouse "cursor may change into a "hand motif to indicate a link. In most graphical web browsers, links are displayed in underlined blue text when they have not been visited, but underlined purple text when they have. When the "user activates the link (e.g. by clicking on it with the mouse) the browser will display the target of the link. If the target is not an HTML file, depending on the "file type and on the browser and its "plugins, another program may be activated to open the file.
The HTML code contains some or all of the five main characteristics of a link:
- link destination ("href" pointing to a URL)
- "link label
- link title
- link target
- link class or link id
It uses the "HTML element "a" with the attribute "href" (HREF is an abbreviation for "Hypertext REFerence") and optionally also the attributes "title", "target", and ""class" or "id":
- <a href="URL" title="link title" target="link target" class="link class">link label</a>
To embed a link into a web page, blogpost, or comment, it may take this form:
In a typical web browser, this would display as the underlined word "Example" in blue, which when clicked would take the user to the example.com website. This contributes to a clean, easy to read text or document.
When the cursor hovers over a link, depending on the browser and graphical user interface, some informative text about the link can be shown, popping up, not in a regular "window, but in a special "hover box, which disappears when the cursor is moved away (sometimes it disappears anyway after a few seconds, and reappears when the cursor is moved away and back). "Mozilla Firefox, "IE, "Opera, and many other web browsers all show the URL. In addition, the URL is commonly shown in the "status bar.
Normally, a link will open in the current "frame or window, but sites that use frames and multiple windows for navigation can add a special "target" attribute to specify where the link will be loaded. If no window exists with that name, a new window will be created with the ID, which can be used to refer to the window later in the browsing session.
Creation of new windows is probably the most common use of the "target" attribute. In order to prevent accidental reuse of a window, the special window names "_blank" and "_new" are usually available, and will always cause a new window to be created. It is especially common to see this type of link when one large website links to an external page. The intention in that case is to ensure that the person browsing is aware that there is no endorsement of the site being linked to by the site that was linked from. However, the attribute is sometimes overused and can sometimes cause many windows to be created even while browsing a single site.
Another special page name is "_top", which causes any frames in the current window to be cleared away so that browsing can continue in the full window.
The term "hyperlink" was coined in 1965 (or possibly 1964) by "Ted Nelson at the start of "Project Xanadu. Nelson had been inspired by ""As We May Think", a popular 1945 essay by "Vannevar Bush. In the essay, Bush described a microfilm-based machine (the "Memex) in which one could link any two pages of information into a "trail" of related information, and then scroll back and forth among pages in a trail as if they were on a single microfilm reel.
In a series of books and articles published from 1964 through 1980, Nelson transposed Bush's concept of automated cross-referencing into the computer context, made it applicable to specific text strings rather than whole pages, generalized it from a local desk-sized machine to a theoretical proprietary worldwide computer network, and advocated the creation of such a network. Though Nelson's Xanadu Corporation was eventually funded by "Autodesk in the 1980s, it never created this proprietary public-access network. Meanwhile, working independently, a team led by "Douglas Engelbart (with "Jeff Rulifson as chief "programmer) was the first to implement the hyperlink concept for scrolling within a single document (1966), and soon after for connecting between paragraphs within separate documents (1968), with "NLS. "Ben Shneiderman working with graduate student Dan Ostroff designed and implemented the highlighted link in the HyperTIES system in 1983. HyperTIES was used to produce the world's first electronic journal, the July 1988 Communications of ACM, which was cited as the source for the link concept in "Tim Berners-Lee's Spring 1989 manifesto for the Web. In 1988, "Ben Shneiderman and Greg Kearsley used HyperTIES to publish "Hypertext Hands-On!", the world's first electronic book.
A database program "HyperCard was released in 1987 for the Apple Macintosh that allowed hyperlinking between various pages within a document. In 1990, "Windows Help, which was introduced with "Microsoft Windows 3.0, had widespread use of hyperlinks to link different pages in a single "help file together; in addition, it had a visually different kind of hyperlink that caused a popup help message to appear when clicked, usually to give definitions of terms introduced on the help page. The first widely used open protocol that included hyperlinks from any Internet site to any other Internet site was the "Gopher protocol from 1991. It was soon eclipsed by HTML after the 1993 release of the "Mosaic browser (which could handle Gopher links as well as HTML links). HTML's advantage was the ability to mix graphics, text, and hyperlinks, unlike Gopher, which just had menu-structured text and hyperlinks.
While hyperlinking among webpages is an intrinsic feature of the "web, some websites object to being linked by other websites; some have claimed that linking to them is not allowed without permission.
Contentious in particular are "deep links, which do not point to a site's "home page or other entry point designated by the site owner, but to content elsewhere, allowing the user to bypass the site's own designated flow, and inline links, which incorporate the content in question into the pages of the linking site, making it seem part of the linking site's own content unless an explicit attribution is added.
In certain "jurisdictions it is or has been held that hyperlinks are not merely "references or "citations, but are devices for copying web pages. In the Netherlands, "Karin Spaink was initially convicted in this way of copyright infringement by linking, although this ruling was overturned in 2003. The courts that advocate this view 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. In 2004, "Josephine Ho was acquitted of 'hyperlinks that corrupt traditional values' in "Taiwan.
In 2000, "British Telecom sued "Prodigy, claiming that Prodigy infringed its patent (U.S. Patent 4,873,662) on web hyperlinks. After "litigation, a "court found for Prodigy, ruling that "British Telecom's patent did not cover web hyperlinks.
In "United States "jurisprudence, there is a distinction between the mere act of linking to someone else's website, and linking to content that is illegal (e.g., gambling illegal in the US) or "infringing (e.g., illegal MP3 copies). Several courts have found that merely linking to someone else's website, even if by bypassing commercial advertising, is not copyright or trademark infringement, regardless of how much someone else might object. Linking to illegal or infringing content can be sufficiently problematic to give rise to legal liability. For a summary of the current status of US copyright law as to hyperlinking, see the discussion regarding "the Arriba Soft and Perfect 10 cases.
Somewhat controversially, "Vuestar Technologies has tried to enforce "patents applied for by its owner, Ronald Neville Langford, around the world relating to search techniques using hyperlinked images to other "websites or web pages.
- "Hyperlink". "Merriam-Webster.com. Retrieved 2012-10-25.
- "Hypergrid - OpenSim". Opensimulator.org. 2012-03-04. Retrieved 2012-10-25.
- "Creating, Saving, and Loading Spaces - Cobalt - DukeWiki". Wiki.duke.edu. 2009-04-21. Retrieved 2012-10-25.
- Wikipedia: the missing manual By John Broughton, 2008, "ISBN 0-596-51516-2, p. 75
- "Tim Berners-Lee. "Making a Server ("HREF" is for "hypertext reference")". W3.org. Retrieved 2012-10-25.
- See "Arriba Soft case. The Ninth Circuit decision in this case is the first important decision of a US court on linking. In it the Ninth Circuit held the deep linking by Arriba Soft to images on Kelly's website to be legal under the fair use doctrine.
- "The prosecution of Taiwan sexuality researcher and activist Josephine Ho" (PDF). Sex.ncu.edu.tw. Archived from the original (PDF) on February 8, 2012. Retrieved 2012-10-25.
- "CNET News.com, Hyperlink patent case fails to click. August 23, 2002.
- Cybertelecom:: Legal to Link? The Internet Archive. Retrieved June 11, 2012.
- Ford Motor Company v. 2600 Enterprises, 177 F.Supp.2d 661 (EDMi December 20, 2001)
- American Civil Liberties Union v. Miller, 977 F.Supp. 1228 (ND Ga. 1997)
- Ticketmaster Corp. v. Tickets.Com, Inc., No. 99-07654 (CD Calif. March 27, 2000)
- Intellectual Reserve v. Utah Lighthouse Ministry, Inc., 75 FSupp2d 1290 (D Utah 1999)
- Universal City Studios Inc v Reimerdes, 111 FSupp2d 294 (DCNY 2000)
- Comcast of Illinois X LLC v. Hightech Elec. Inc., District Court for the Northern District of Illinois, Decision of July 28, 2004, 03 C 3231
- WebTVWire.com, Linking to Infringing Video is probably Illegal in the US. December 10, 2006.
- Compare Perfect 10 v. Google, Decision of February 21, 2006, Case No. CV 04-9484 AHM (CD Cal. 2/21/06), CRI 2006, 76–88 No liability for thumbnail links to infringing content
- TelecomTV - TelecomTV One - News
- All your Interwibble is belong to us, Silvie Barak, "The Inquirer, 21 February 2009
- Weinreich, Harald; Hartmut Obendorf; Winfried Lamersdorf (2001). "The look of the link – concepts for the user interface of extended hyperlinks": 19. "doi:10.1145/504216.504225. "ISBN "9781581134209. Retrieved 2010-09-04.