GIF files are the most popular image type used on Web sites, due to support for them existing in all graphical Web browsers. Hit A single connection between a Web browser and the content server to which it connects, which results in the transmission of a resource from the content server to the browser. The resource can be text, an image, or any other individual element that can be included in a Web page. A request can result in the successful delivery of content to the user, or an error. A successful request to a page containing an ad is counted as an impression for that ad.
Most Web servers log each request to an access log file.
HTML Hyper Text Markup Language. Any text that can be chosen by a reader and which cause another document to be retrieved and displayed. IAB Internet Advertising Bureau. The IAB is a global nonprofit association devoted exclusively to maximizing the use and effectiveness of advertising in the Internet. The IAB sponsors research and events related to the Internet Advertising.