Google AdWords is an advertising avenue where you can predetermine your budget for advertising and set the amount you are willing to pay per click to your site. The AdWords campaign tells you how much it will cost to be on the first page as well as a very detailed description on which keywords are getting the best results so you can redefine your pay-per-clicks accordingly to those key words.  Google recommends that if you are #1 on the first page, you may be paying too much per click.  An optimum placement of #5-#7 (still on the first page) will be much more cost-efficient.

Click on the scaled photo below to see it full sized