"The process of exchanging reciprocal links with Web sites in order to increase search engine optimization. The idea behind link farming is to increase the number of sites that link to yours because search engines such as Google rank sites according to, among other things, the quality and quantity of sites that link to yours. In theory, the more sites that link to yours, the higher your ranking in the search engine results will be because the more links indicate a higher level of popularity among users of the Internet. However, search engines such as Google consider link farming as a form of spam and have been implementing procedures to banish sites that participate in link farming, so the term link farming has garnered negative connotations across the Internet." --Webopedia
"Bad links can also be found in link farms...If your site has attracted link farmers' attention, get it removed from these communities. About 70 percent of link farm Webmasters will remove your site with a simple email request. The other 30 percent usually respond to a saber-rattling message from your attorney. If revenge is what you seek, report the link farm as spam to the search engines -- after links to your site have been removed." --P.J. Fusco, "Meta Tags and Link Deficiency Confusion"