There are dozens of things that play a part in the effectiveness of a keyword in SEO. The most important, however, is finding keywords that cater to targeted traffic. Targeted traffic are the people who visit your website because they are interested in purchasing or reading the products or information you offer. A keyword “converts” when a customer uses it in a search, is directed to your website, and ends up finding and purchasing a product or service you offer. Obviously, those are the keywords you want.