Pay-per-click is when a company places an advertisement on a website and pays a sum of money to the host website when a user clicks on to the advertisement. It’s abbreviated in the industry as PPC.

Pay-per-click ads are most effective when the ads are served through an ad network and placed on websites where the users who see them are interested in a similar product or topic.

The two most important PPC ad networks are Google Adwords and Bing Network, each offering ads displayed on their SERPs (search engine results pages).