Negative keywords are words that do not apply to your product or service offering. For example, if you offer travel packages, you would not want people searching for “free travel” to find your site. Therefore including “free” as a negative keyword in your tags will narrow and focus the number of visitors to your site by not presenting your ad as an option to web users seeking free travel. Applying such focused matching options will help you reach the most appropriate prospects, reduce your PPC expenses, and increase your ROI. Google AdWords and Overture both allow you to include negative keywords in your ads.