Alphabet, formerly called Google, maintains the largest online index of websites accessible through automated search technology. It generates revenue through online advertising, cloud services, and hardware. Google is now an operating segment of Alphabet. The company was founded in 1998 by Sergey Brin and Larry Page and went public in 2004. Google's AdWords is an auction-based program that lets businesses display ads along with particular search results. Google's AdSense program enables websites in the company's network to serve targeted ads, based on search terms or web content, from AdWords advertisers. Most of the revenue generated through AdSense is shared with network partners. In addition, Alphabet owns YouTube.com, the web-based video site. It has also expanded into mobile telephony with its Android smartphone operating system and into public cloud services. About 54% of Alphabet's revenue is generated outside the U.S. On April 3, 2014, Alphabet's new nonvoting class C shares began trading under the