adwords is an advertising network owned and run by google. They offer text ads which are displayed alongside their search results (search network) or on other people's sites (content network). If you want to market something on the internet, one option is to use the ad network. These type of ads are normally called ppc (per per click) advertising ie. you only pay when a prospective customer clicks your ad.
AdWords is Google's main advertising product and main source of revenue. AdWords offers pay-per-click (PPC) advertising, cost-per-thousand (CPM) advertising, and site-targeted advertising for text, banner, and rich-media ads. The AdWords program includes local, national, and international distribution. Google's text advertisements are short, consisting of one headline and two additional text lines. Image ads can be one of several different Interactive Advertising Bureau (IAB) standard sizes.