Google Inc. is in the business of indexing websites and other web content, which is freely available to anyone on the Internet. Through Google's web index, the company's automated search technology helps users get the relevant information they search for instantly. Businesses market their products and services through Google's advertising keywords business, and thousands of third-party websites that are part of Google's network can use Google's enterprise advertising network business to publish their own relevant ads. Google's revenue comes mainly from publishing online advertising. Google acquired email security company Postini Inc and online advertising company DoubleClick in 2007 and 2008, respectively. Some of Google's specific businesses include: Google Web Search, Google Image Search, Google Finance, Google Docs, Google User Group, Google Desktop, Google Toolbar, Google Earth, Google Checkout, Google Mobile, Google Labs, Google Ads Keywords , Google Ad Network, Google Enterprise, Google Apps, etc. The company was founded in 1998 and is headquartered in Mountain View, California.