Security is an essential part of an application and it should be taken into  consideration from the grass root level from an application’s design. Security  is all about protecting your assets from unauthorized actions.

But Code Access Security (CAS) is a feature of .NET CLR which enables you to  control the permissions which an individual .NET application have on your system  during its execution. As a developer, you must understand how to create  applications that work even when some permission is restricted or to restrict  your application to perform certain tasks for example, a user can’t  delete/create a file in C:\Windows directory Read Full Article Here