Pay Per Click (PPC) Advertising
Pay per click is a little like SEO except that you pay each time someone clicks to visit your website.
PPC however is far more controllable and extremely targeted. Your ad is only seen by people searching for your product or service. PPC can be an extremely effective marketing tool when carried out correctly. Beware there are some companies who offer a set fee for page 1 on the search engines. You should only pay once for the campaign to be set up for you and then a reasonable management fee depending on your monthly ad spend. The rest, you should pay direct to the search engines.