Pay per click is a form of advertisement that is done over the Internet. Each advertisement is not done free. In fact all the sites charge for ads and stuff. But pay per click advertisement is the cheapest form of advertisement that is used today. It is not only being used by websites and search engines but also by the Internet users who are smart and know how to make money by using pay per click.
The pay per click advertisement was introduced by a smaller company in 1998. But today it is being used by the big names like Google Adwords and Yahoo. The search engines that use it include Ask and Looksmart. Pay per click is cheap and costs less than other advertising methods but it does not guarantee that it will be successful especially when it comes to making purchase of items.

Search engines use pay per click in the form of bidding. If you want to put your ad at some website, you will have to submit it to the concerned authority. You will also provide different keywords that you want to be a part of the advertisement. You will be asked to mention some amount of money that you will pay to the website for each click you get. By click it means anyone who opens your advertisement and checks it. Depending on different websites, your advertisement is given a place at the top or somewhere at the center to gather the attention of maximum visitors.
Some websites on the other hand charge a fixed amount of money from the advertisers and do not go for the bidding system.
So this was some information about the pay per click form of advertisement. I am sure that you would have found the article interesting.