Deep linking

In the context of the World Wide Web, deep linking is the use of a hyperlink that links to a specific, generally searchable or indexed, piece of web content on a website (e.g., "http://example.com/path/page"), rather than the website's home page (e.g., "http://example.com/").

The technology behind the World Wide Web, the (HTTP), does not actually make any distinction between "deep" links and any other links—all links are functionally equal. This is intentional; one of the design purposes of the Web is to allow authors to link to any published document on another site. The possibility of so-called "deep" linking is therefore built into the Web technology of HTTP and URLs by default—while a site can attempt to restrict deep links, to do so requires extra effort. According to the World Wide Web Consortium Technical Architecture Group, "any attempt to forbid the practice of deep linking is based on a misunderstanding of the technology, and threatens to undermine the functioning of the Web as a whole".

Some commercial websites object to other sites making deep links into their content either because it bypasses advertising on their main pages, passes off their content as that of the linker or, like The Wall Street Journal, they charge users for permanently valid links. Sometimes, deep linking has led to legal action such as in the 1997 case of Ticketmaster versus Microsoft, where Microsoft deep-linked to Ticketmaster's site from its Sidewalk service. This case was settled when Microsoft and Ticketmaster arranged a licensing agreement. Ticketmaster later filed a similar case against Tickets.com, and the judge in this case ruled that such linking was legal as long as it was clear to whom the linked pages belonged. The court also concluded that URLs themselves were not copyrightable, writing: "A URL is simply an address, open to the public, like the street address of a building, which, if known, can enable the user to reach the building. There is nothing sufficiently original to make the URL a copyrightable item, especially the way it is used. There appear to be no cases holding the URLs to be subject to copyright. On principle, they should not be."

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