A web application is a collection of static and dynamic web pages. A static web page is one that does not change when a site visitor requests it: The web server sends the page to the requesting web browser without modifying it. In contrast, a dynamic web page is modified by the server before it is sent to the requesting browser. The changing nature of the page is why it’s called dynamic.

For example, you could design a page to display fitness results, while leaving certain information (such as employee name and results) to be determined when the page is requested by a particular employee.

The next sections describe how web applications work in greater detail.