Backlinking: and why it's important

Linking fuels search engine results. Search engines rely
on automated means of assessing the relative merits of
individual pages and sites, and one metric that they all use in making those determinations is the number of links pointing to the page or site.

If millions of people are linking somewhere, the search
engines assume the site must be valuable and they reward it
accordingly. If a site doesn’t have a single link pointing
in it’s direction, then it will be more than hard-pressed to be able to move it’s way into any meaningful search results.