It is both relevance and popularity that the process of SEO is meant to influence.

oes two things: first, it returns only those results that are relevant or useful to the searcher's query; second, it ranks those results according to the popularity of the websites serving the information.

Search engines are answer machines.

Links allow the search engines' automated robots, called "crawlers" or "spiders," to reach the many billions of interconnected documents on the web.