Do a search on Google or Yahoo, and you’ll notice a different type of listings ({Pay-Per-Click ads) set around the organic results. These “sponsored results” are paid ads that appear when people search using keywords in the ads.

There are also special search engines, like Miva, Enhance, and GoClick, where all the listings are paid for.

Pay-Per-Click advertisers look for keywords that they believe their target market uses to search for them online.