Back-links
Back-links, also called inbound links, includes any link on the Internet that points to any page within your web site.
The number of backlinks that a particular web site has pointing to it tends to be indicative of its popularity on the Internet. Many search engines view back-links as a “vote” for a web site, provided that link comes from a relevant and reputable web site rather than a link farm. The more backlinks that a particular web site receives, the higher it tends to appear in the search engine results.