They are offered to
advertisers as an auction opportunity, and determine whether they come out in a top-rank search engine spot or not.
Advertisers understandably want to have some solid information on the results of the use of their money for the adword. Google has developed a program called an adwords tracking tool that offers them valuable analytical data.
The adwords tracking tool will provide in just a few seconds the number of hits, those actually clicking on their website.

Since each response (click) can cost the advertiser anywhere from 1 penny to $50.00, they get very serious.
With the adword tracking tool, Google can provide the advertiser with how long a searcher stays on their site, whether or not they purchase anything, which adwords bring better results, and how much the adword costs in relationship to

the sales it generates.
Google can also supply a list of adwords likely to generate traffic and ones that are very weak.