Google AdWords is an online advertising service that enables advertisers to compete to display brief advertising copy to web users, based in part on cookies and keywords predefined by the advertisers. Web pages from Google and from partner websites are designed to allow Google to select and display this advertising copy. Advertisers pay when users divert their browsing to seek more information about the copy displayed, and partner websites receive a portion of the income they generate.
AdWords has evolved into Google's main source of revenue, contributing to Google's total advertising revenues of USD $43.7 billion in 2012.[2] AdWords offers pay-per-click (PPC) (cost-per-click (CPC) advertising), cost-per-acquisition (CPA) advertising,[3] cost-per-thousand-impressions or cost per mille (CPM) advertising, site-targeted advertising for text, banner, and rich-media ads, and remarketing (also known as retargeting). The AdWords program includes local, national, and international distribution. Google's text advertisements are short, and consist of one headline of 25 characters, two additional text lines of 35 characters each, and a display URL of 35 characters. Image ads can be one of several different Interactive Advertising Bureau (IAB) standard sizes. In May 2016, Google announced its reformatting of ads to help consumers and advertisers succeed in a mobile-first world. The new format, called Expanded Text Ads, allows for 23% more text. The new format is available on both the Google Search Network and the Google Display network. It features two headlines with 30 characters each, to replace the single headline of 25 characters. The new description allows 80 characters and replaces the two descriptions lines of 35 characters each. The display URL is replaced with two 15 character paths, and the characters do not include the root domain.