The term Search Engine Marketing (SEM) is a form of internet marketing that focuses upon visibility in search engines like Google, Bing, and Yahoo. Of course, search engines are fairly complex and the many algorithms that determine which websites to list first are ever changing. Because it is complicated, many companies opt to outsource to fill their marketing needs. While SEM is an umbrella term that can refer to any methods used to achieve high search engine rankings. However, those who work in online marketing usually use this term to mean the strategic use of paid advertisements in search engines. The most common form of SEM is Pay-Per-Click advertising. This works just as it sounds. Every time a visitor comes to your website through the ad, you pay a fee. The benefit of this is that you only pay for results.