Pay per click (PPC) is another form of Internet Advertising that’s used on Web sites where advertisers pay their host only when their ad is clicked. With the search engines, advertisers will bid on keyword phrases relevant to their target market. Most content sites will charge a fixed price per click rather than use a bidding system.
Web sites that use PPC ads will display an advertisement when a keyword search matches an advertiser’s keyword list, or when a content site displays relevant content. These advertisements, also called sponsored links or sponsored ads, will appear next to or above organic results on the search engine results pages or anywhere a web developer chooses on a content site.
While there are a lot of PPC providers, Google AdWords, YAHOO! Search Marketing and Microsoft adCenter are three of the largest network operators; all three operate under a bid-based model.
Even though Google and others implemented automated systems to guard against abusive clicks, PPC advertising is still open to abuse through click fraud by competitors or corrupt web developers.