Backlinks have always had some bearing on how well a site ranked in search engine
result pages (SERPs). However, in the past, the algorithms were not designed to
take into account people trying to cheat the system by loading up on backlinks from
sites that had nothing but links on them, no content of any real relevance. These
sites quickly became known as “link farms” and were used by webmasters to
increase the ranking of their multiple sites.
In addition to this practice, webmasters often created one web page specifically to
house reciprocal links called a links page. It was used by people building reciprocal
links to better leverage their site in search engine results but provided no real
content. Sometimes, reciprocal links were even exchange between sites that had no
direct relevance to each other too. So, in a links page you might find a link to a toy
site when the website hosting the link had to do with the elderly. It obviously made
no sense to reward this type of behind the scenes ranking manipulations!
Google was one of the first major search engines to start looking at how to reward
good quality links that had relevance and added content to a site instead of
rewarding savvy, but somewhat unscrupulous practices of cheating the search
engine results with backroom deals and black hat tricks. They kept using backlinks
as a determinant of reputation, but also strengthened the algorithm to look for
specific quality links and penalizing link farms and other black hat maneuvers.