Backlinks are incoming links that point to your web page. If many other sites point to your website, it is assumed by search engine algorithms that these sites value the content or products on your site. Search engine rankings are positively affected by a large number of backlinks, as well as the quality of these links. There are two ways for a site to get a higher number of backlinks:
Some backlinks are created when another site links to yours because you have information of product they feel their visitors want. These sites provide links to complementary sites, not competitors. Some sites work together to exchange links, by mutual agreement. These are called reciprocal links, and they have benefits in search engine ranking as well as in business generation.

The quality of backlinks is dependent upon the origination of a link to your site. If the site linking to yours is a complex, quality site, it is more valuable to your search engine ranking than a one page mini-site. And a higher quality site with a complementary focus will, just like a reciprocal link, deliver you more potential for economic benefit, search engines aside. If a site links to hundreds or thousands of sites, its value to you as a backlink in a search engine will be diminished.

Do your homework before you proceed. Check to see which companies link to your site, and check the sites of potential reciprocal link sites at www.linkpopularity.com. You can even sign up for a monthly update of your statistics.