A web banner or banner ad is a form of advertising on the World Wide Web delivered by an ad server. This form of online advertising entails embedding an advertisement into a web page. It is intended to attract traffic to a website by linking to the website of the advertiser. In many cases, banners are delivered by a central ad server. When the advertiser scans their logfiles and detects that a web user has visited the advertiser's site from the content site by clicking on the banner ad, the advertiser sends the content provider some small amount of money. This payback system is often how the content provider is able to pay for the Internet access to supply the content in the first place. Usually though, advertisers use ad networks to serve their advertisements, resulting in a revshare system and higher quality ad placement.