SEO (Search Engine Optimization) has many aspects to it. The most important and influential one is the back links a site has i.e the number of other sites that are linking to a site. This is the key algorithm behind "Page Rank" and it is was the main ranking factor used be Google for many years. Though they claim that back links are now only one of over 200 signals that they evaluate to determine the rank of a website in the search results, it still seems to be one of the most important factors. These tools called back link checkers are tell users which sites link to a particular page. These are to evaluate website and competitor websites to see who is linking to them. Analyzo has listed some of the best tools to evaluate Back Links to a site.