ASP.NET is an open source web framework for building modern web applications and services. With ASP.NET you can quickly create web sites based on HTML, CSS and JavaScript, scale them to millions of users and easily add more complex capabilities like Web APIs, forms over data or real time communications.

ASP and ASP.NET are server side technologies. Both technologies enable computer code to be executed by an Internet server. When a browser requests an ASP or ASP.NET file, the ASP engine reads the file, executes any code in the file, and returns the result to the browser.