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.

C# (pronounced "C-sharp") is an object-oriented programming language from Microsoft that aims to combine the computing power of C++ with the programming ease of Visual Basic. C# is based on C++ and contains features similar to those of Java.