Backlink
Encyclopedia
Backlinks, also known as incoming links, inbound links, inlinks, and inward links, are incoming links
Hyperlink
In computing, a hyperlink is a reference to data that the reader can directly follow, or that is followed automatically. A hyperlink points to a whole document or to a specific element within a document. Hypertext is text with hyperlinks...

 to a website
Website
A website, also written as Web site, web site, or simply site, is a collection of related web pages containing images, videos or other digital assets. A website is hosted on at least one web server, accessible via a network such as the Internet or a private local area network through an Internet...

 or web page
Web page
A web page or webpage is a document or information resource that is suitable for the World Wide Web and can be accessed through a web browser and displayed on a monitor or mobile device. This information is usually in HTML or XHTML format, and may provide navigation to other web pages via hypertext...

. In basic link terminology, a backlink is any link received by a web node (web page, directory, website, or top level domain) from another web node.

Inbound links were originally important (prior to the emergence of search engines) as a primary means of web
World Wide Web
The World Wide Web is a system of interlinked hypertext documents accessed via the Internet...

 navigation; today, their significance lies in search engine optimization
Search engine optimization
Search engine optimization is the process of improving the visibility of a website or a web page in search engines via the "natural" or un-paid search results...

 (SEO).
The number of backlinks is one indication of the popularity or importance of that website or page (for example, this is used by Google to determine the PageRank
PageRank
PageRank is a link analysis algorithm, named after Larry Page and used by the Google Internet search engine, that assigns a numerical weighting to each element of a hyperlinked set of documents, such as the World Wide Web, with the purpose of "measuring" its relative importance within the set...

 of a webpage). Outside of SEO, the backlinks of a webpage may be of significant personal, cultural or semantic interest: they indicate who is paying attention to that page.

Search engine rankings

Search engine
Search engine
A search engine is an information retrieval system designed to help find information stored on a computer system. The search results are usually presented in a list and are commonly called hits. Search engines help to minimize the time required to find information and the amount of information...

s often use the number of backlinks that a website has as one of the most important factors for determining that website's search engine ranking, popularity and importance. Google
Google
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...

's description of their PageRank
PageRank
PageRank is a link analysis algorithm, named after Larry Page and used by the Google Internet search engine, that assigns a numerical weighting to each element of a hyperlinked set of documents, such as the World Wide Web, with the purpose of "measuring" its relative importance within the set...

 system, for instance, notes that Google interprets a link from page A to page B as a vote, by page A, for page B. Knowledge of this form of search engine rankings has fueled a portion of the SEO industry commonly termed linkspam, where a company attempts to place as many inbound links as possible to their site regardless of the context of the originating site.

Websites often employ various search engine optimization
Search engine optimization
Search engine optimization is the process of improving the visibility of a website or a web page in search engines via the "natural" or un-paid search results...

 techniques to increase the number of backlinks pointing to their website. Some methods are free for use by everyone whereas some methods like linkbaiting requires quite a bit of planning and marketing to work. Some websites stumble upon "linkbaiting" naturally; the sites that are the first with a tidbit of 'breaking news' about a celebrity are good examples of that. When "linkbait" happens, many websites will link to the 'baiting' website because there is information there that is of extreme interest to a large number of people.

There are several factors that determine the value of a backlink. Backlinks from authoritative sites on a given topic are highly valuable. If both sites have content geared toward the keyword topic, the backlink is considered relevant and believed to have strong influence on the search engine rankings of the webpage granted the backlink. A backlink represents a favorable 'editorial vote' for the receiving webpage from another granting webpage. Another important factor is the anchor text of the backlink. Anchor text
Anchor text
The anchor text, link label or link text is the visible, clickable text in a hyperlink. The words contained in the anchor text can determine the ranking that the page will receive by search engines. Since 1998, some web browsers have added the ability to show a tooltip for a hyperlink before it is...

 is the descriptive labeling of the hyperlink as it appears on a webpage. Search engine bots (i.e., spiders, crawlers, etc.) examine the anchor text to evaluate how relevant it is to the content on a webpage. Anchor text and webpage content congruency are highly weighted in search engine results page (SERP) rankings of a webpage with respect to any given keyword query by a search engine user.

Increasingly, inbound links are being weighed against link popularity and originating context. This transition is reducing the notion of one link, one vote in SEO, a trend proponents hope will help curb linkspam as a whole.

It should be noted that although many people will say building too many links too quickly will get you penalized, it actually will not. If it were possible to be penalized for building too many incoming links, people would target their competition for penalties by building "too many" links.

Technical

When HTML
HTML
HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....

 (Hyper Text Markup Language) was designed, there was no explicit mechanism in the design to keep track of backlinks in software, as this carried additional logistical and network overhead.

Most Content management system
Content management system
A content management system is a system providing a collection of procedures used to manage work flow in a collaborative environment. These procedures can be manual or computer-based...

s include features to track backlinks, provided the external site linking in sends notification to the target site. Most wiki
Wiki
A wiki is a website that allows the creation and editing of any number of interlinked web pages via a web browser using a simplified markup language or a WYSIWYG text editor. Wikis are typically powered by wiki software and are often used collaboratively by multiple users. Examples include...

 systems include the capability of determining what pages link internally to any given page, but do not track external links to any given page.

Most commercial search engines provide a mechanism to determine the number of backlinks they have recorded to a particular web page. For example, Google
Google
Google Inc. is an American multinational public corporation invested in Internet search, cloud computing, and advertising technologies. Google hosts and develops a number of Internet-based services and products, and generates profit primarily from advertising through its AdWords program...

 can be searched using link:wikipedia.org to find the number of pages on the Web pointing to http://wikipedia.org/. To find link information on Yahoo type linkdomain:http://www.wikipedia.org. Google only shows a small fraction of the number of links pointing to a site. It credits many more backlinks than it shows for each website.

Other mechanisms have been developed to track backlinks between disparate webpages controlled by organizations that aren't associated with each other. The most notable example of this is TrackBack
TrackBack
A trackback is one of three types of linkback methods for Web authors to request notification when somebody links to one of their documents. This enables authors to keep track of who is linking to their articles...

s between blogs.

See also

  • Link farm
    Link farm
    On the World Wide Web, a link farm is any group of web sites that all hyperlink to every other site in the group. Although some link farms can be created by hand, most are created through automated programs and services. A link farm is a form of spamming the index of a search engine...

    s
  • Methods of website linking
    Methods of website linking
    This article pertains to methods of hyperlinking to/of different websites, often used in regard to search engine optimization . Many techniques and special terminology about linking are described below.-Reciprocal link:...

  • PageRank
    PageRank
    PageRank is a link analysis algorithm, named after Larry Page and used by the Google Internet search engine, that assigns a numerical weighting to each element of a hyperlinked set of documents, such as the World Wide Web, with the purpose of "measuring" its relative importance within the set...

  • Search Engine Optimization
    Search engine optimization
    Search engine optimization is the process of improving the visibility of a website or a web page in search engines via the "natural" or un-paid search results...

  • Linkback
    Linkback
    A linkback is a method for Web authors to obtain notifications when other authors link to one of their documents. This enables authors to keep track of who is linking to, or referring to, their articles...

  • Search engine results page
    Search engine results page
    A search engine results page , is the listing of web pages returned by a search engine in response to a keyword query. The results normally include a list of web pages with titles, a link to the page, and a short description showing where the Keywords have matched content within the page...

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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