Google AdWords is Google's main advertising product
and main source of revenue. Google's total advertising revenues were USD$28 billion in 2010.[2] AdWords offers pay-per-click (PPC) advertising, cost-per-thousand (CPM) advertising, and site-targeted advertising for text, banner, and rich-media ads. The AdWords program includes local, national, and international distribution. Google's text advertisements are short, consisting of one headline consisting of 25 characters and two additional text lines consisting of 35 characters each. Image ads can be one of several different Interactive Advertising Bureau (IAB) standard sizes.
Sales and Support for Google's AdWords division is based in Mountain View, California, with major secondary offices in Ann Arbor, Michigan,[3] the company's third-largest US facility behind its Mountain View, California, headquarters and New York City office.[4] Engineering for AdWords is based in Mountain View, California.
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http://en.wikipedia.org/wiki/AdSense
Google AdSense is an ad serving application run by Google Inc. Website owners can enroll in this program to enable text, image, and video advertisements on their websites. These advertisements are administered, sorted, and maintained by Google, and they can generate revenue on either a per-click or per-impression basis. Google beta tested a cost-per-action service, but discontinued it in October 2008 in favor of a DoubleClick offering (also owned by Google).[2] In Q1 2011, Google earned US$2.34 billion ($9.36 billion annualized), or 28% of total revenue, through AdSense.[3]