My thoughts on conversion tracking
The way a search engine works is that it sorts the relevance of a web site to the keyword that is being searched. How much a site is relevant to a keyword depends on the density of that word in the web site. A web site that uses a particular phrase or word, say "quality healthcare" a lot on their site will be found higher on a result list for someone who types "quality healthcare" into their search engine. When a web site appears towards the top of a search result list it generally receives more traffic. More web site traffic will increase the probability that your product will be sold or that your idea will be spread.