Pay per click advertising is a popular way of driving traffic for all ecommerce websites. It works by companies placing advertisements on search engines but only paying when customers click on them. Advertisers choose search terms that they believe their potential customers will be searching for and bid on those terms (known as keywords). The advertisements of the highest bidders are placed at the top of the page when customers search on those terms.

The links to each ad are called sponsored links.

The main pay-per-click advertising companies are Google AdSense, Yahoo Search Marketing and Microsoft adCentre.