Google AdWords’ system is partly based 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 the advertising copy selected.
AdWords offers pay-per-click (PPC) (cost-per-click (CPC) advertising), cost-per-acquisition (CPA) advertising, cost-per-thousand-impressions, or cost per mille (CPM) advertising, site-targeted advertising for text, banner, and rich-media ads, and re-marketing (also known as re-targeting)
The AdWords program includes local, national, and international distribution. Google’s text advertisements are short, consisting of one headline of 30 characters, two additional text lines of 40 characters each, and a display URL of 40 characters.