In 2000, Google launched their AdWords product. AdWords is Google's flagship advertising product and main source of thier revenue. It works through advertisements, where advertisers woulds pay a monthly amount, and Google would set up and manage thier campaign.

AdWords offers pay-per-click (PPC) advertising, and site-targeted advertising for both text and banner ads. PPC is an advertising model where advertisers only pay when a user actually clicks on an ad to visit the advertiser's website. Banner ad is a form of advertising on the World Wide Web and intended to attract traffic by linking them.

The program has local, national, and international distribution. In advertising process, text advertisements must be short, consisting of one title line, and two content text lines. For image ads, images can be one of several different Interactive Advertising Bureau (IAB) standard sizes. IAB is an advertising business organization founded in 1996 that develops industrial standards, conduct research, and provides legal support for the online advertising industry.

Advertising goes like these, advertisers specify the keywords should trigger thier ads those are the words or phrases related to their business and the maximum amount they are willing to pay per click. Then when a user searches Google's search engine on www.google.com those relevant words are shown as "sponsored links" on the right side of the screen, and sometimes above the main search results.

By then, user can simply click the advertiser's ad to make a purchase or learn more about the sponsored link or the ad. Again an advertiser charged only if someone clicks the ad, not when and while the ad is displayed.

As Google's main sourse of revenue, competitors also created their own products. Yahoo created the Yahoo Search Marketing while the Microsoft created Microsoft adCenter.