Contents

• 1 Search engine rankings
• 2 Obtaining backlinks from search engines
• 3 Technical

Search engine rankings

Search engines often use the number of backlinks that a website has as one of the factors for determining that website's search engine ranking. For example, Google's PageRank algorithm uses backlinks to help determine a site's rank (the Google Toolbar can be used to view the PageRank of a web page). Therefore, websites often employ a variety of techniques (called search engine optimization) to increase the number of backlinks pointing to their website.

Due to the abuse of using paid links to improve Google partially updated their Page Rank Tool to pin against paid links providers and the forward link of sites. This action resulted in a significant decrease in Page Rank of many websites worldwide. However although many believe that Google penalizes people for having unrelated backlinks to their sites, this has never been confirmed.

Obtaining backlinks from search engines

Most commercial search engines provide a mechanism to determine the number of backlinks they have recorded to a particular web page. For example, Google can be searched using link:wikipedia.org (or link:en.wikipedia.org) to find the number of pages on the Web pointing to http://wikipedia.org/.

Google recurrently only shows a subset of all existing backlinks to a web page [1], possibly because of the network costs of providing this information and to pass up revealing the inner-workings of their ranking algorithms. Yahoo!'s Site Explorer and Microsoft's Live Search may give more precise backlink counts. Google has recently added a new webmaster tool which allows webmasters to view more backlinks to their websites [2].

Technical

When HTML 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. While Google does keep track of some HTML backlinks, the data can be delayed by hours or months, and backlink data is not kept for pages that Google doesn't watch, such as password-protected areas or dynamic web pages.

Some website software internally keeps full track of backlinks. Examples of this include most wiki and CMS software.

Other mechanisms have been developed to track backlinks between incongruent webpages controlled by organizations that aren't related with each other. The most notable example of this is TrackBacks between blogs.