A Web application page is different from a static Web page because it can publish data dynamically. This involves creating, manipulating, and outputting variables.
A variable stores data that can be used in applications. As with other programming languages, you'll set variables in ColdFusion to store data that you want to access later. And you'll reference a range of variables to perform different types of application processing.
For example, you would store a user's preferences in a variable in order to use that data to customize the page that's returned to the browser.