What is link farming?
Link farming is questionable search engine optimization (SEO) in which one website enters into a reciprocal relationship with another website or pays a provider for a large number of inbound links. Because many search engines use inbound links as a factor in determining a website's page rank, websites use link farming to improve their rankings in search engine results.
While relevant inbound links are an important component of website SEO, this should not be confused with listing a site on a link farm that merely links to other sites in a group.
Search engines like Google view link farming as a form of spam. Google and others have put in place procedures to penalize websites that receive inbound links through farms, rather than organically or through link campaigns with other quality websites.
Service providers who promise to improve a website's search engine rank can use link farming. In this case, the provider simply books links on other, unrelated websites, some of which are only intended for this purpose.
Search engines used to be very vulnerable to link farming because it relied primarily on the argument that a page has greater authority when a large number of other sites link to it. Link farming often fails because search engines present the results based on the most useful to the user. This means that a link from a site with trusted content or similar content to the page it is linked to is worth more than random links from many sites.
When webmasters try to artificially inflate the number of backlinks to their website through link farming, search engines punish this behavior when they recognize it. A violation could result in a website's page rank being dropped or even removed for some time.
Essentially, search engines are trying to encourage websites to gain authority - and therefore page rank - in the most legitimate way possible. The ideal way to get a page rank is by building great content websites that are often referred to by other high quality websites.