Pay per click (PPC) is an advertising model used on search engines, advertising networks, and content websites/blogs, where advertisers only pay when a user actually clicks on an ad to visit the advertiser's website. Its generally use to get instant traffic though your site does not have organic ranking. There are many companies exists in the area, Google AdWords and Yahoo Search Marketing are the biggest advertising networks, mean while MSN has also started their own in-house services called MSN adcenter in the spring of 2006. PPC engines can be categorized into two major categories "Keyword" or “sponsored match” and "Content Match". Sponsored match displays your listing on the search engine itself whereas content match features ads on publisher sites and in newsletters and emails.