Hello,
In broad terms, whenever any user enters a query into a search engine, the search engine needs to determine how to return the best results. One key step is to figure out which pages on the web are related in any way to the query. Another key step is to evaluate which of the pages that relate to the query are the most important, or the most authoritative in regard to that query. One of the biggest factors in deciding that is the link profile of the site containing the web page being evaluated, and the link profile of that page itself.
Thanks,