ASP.Net is a server side Technology to develop a web based applications.ASP.Net will make use of .Net framework features.
Advantages of ASP.Net
ASP.NET makes development simpler and easier to maintain with an event-driven, server-side programming model
ASP.NET offers built-in security features through windows authentication or other authentication methods.
Content and program logic are separated which reduces the inconveniences of program maintenance.
Built-in caching features.