Google AdWords – An online advertising service that places advertising copy above, below, or beside the list of search results Google displays for a particular search query, or it displays it on their partner websites. The choice and placement of the ads is based in part on a proprietary determination of the relevance of the search query to the advertising copy. AdWords has evolved into Google’s main source of revenue. Google’s total advertising revenues were USD $43.7 billion in 2012. AdWords offers pay-per-click (PPC), that is, cost-per-click (CPC) advertising, 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, consisting 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.