With Google AdWordsTM, you set the price you're willing to pay for a sales lead - as little as 5¢ per lead, which you pay only when someone clicks your ad to visit your site and until your daily budget is reached. The most popular search terms attract many bids, and top placement may cost more. If you don't have the top bid, your ad might appear lower on the list of sponsored links, but you never pay more than your own maximum price per click or daily budget. AdWords positions are based on a combination of click through rate and bid price, so your ad can rise above someone paying more if it is highly relevant for a specific keyword.
Google's simple online tools show you expected costs and average number of clicks for keywords you are considering. Google's conversion tracking tool allows you to track how many ad clicks convert to purchases, sign-ups, page views, and leads - for free. Google also makes sure you never pay more than you have to by automatically monitoring your competition and lowering your cost per click to one cent above your nearest competitor.