Backlinks are incoming links to a website or web page. In the search
engine optimization (SEO) world, the number of backlinks is one
indication of the popularity or importance of that website or page
(though other measures, such as PageRank, are likely to be more
important). 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.
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 (Björneborn and Ingwersen, 2004). Backlinks are also known as
incoming links, inbound links, inlinks, and inward links.
Search engines 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. Websites often employ various techniques (called
search engine optimization, usually shortened to SEO) 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 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 your webpage with respect to any
given keyword query by a search engine user.