C#

C# was designed to provide a simple, clean, general purpose programming language for those intending to work within the confines of Microsoft’s .NET framework. It was designed for programmers to be able to use it to create different components for use in software that would be deployed and distributed en masse. C# has attempted to bridge the gap between full featured visual languages and assembly code by being economical in terms of requirements.

ASP.NET

ASP.NET is an open-source server-side web application framework designed for web development to produce dynamic web pages. It was developed by Microsoft to allow programmers to build dynamic web sites, web applications and web services. ASP.NET aims for performance benefits over other script-based technologies (including Classic ASP) by compiling the server-side code the first time it is used to one or more DLL files on the Web server.

WHERE USED

ASP.NET is a great framework to use across the board when developing web sites, or web applications. It is reliable, fast, easy to use, and widely known. ASP.NET gives you full control of your development and can easily be used on any project, big or small.
ASP.NET allows a developer to choose from many different development environments, also its popularity gives a developer tons of online resources when learning new things, or troubleshooting bugs.