Pay-per-click (PPC) marketing is actually advertising over the internet where in advertisers pay the publisher when their ad is clicked by the audience. It is also known as cost per click marketing. Basically, in PPC marketing your ads are shown on other websites and if the user clicks on it the advertiser has to pay fixed rate for each click.
The basic idea behind it is to drive more and more traffic to your website and generate more leads converting them into sales eventually. It is definitely an incredible tool for marketers who are willing to invest and get a good traffic to their site leading to sales.