Answer:   ASP.NET introduces a concept of application domain or AppDomain which is like a lightweight process that acts like both container and boundary. The .NET run-time uses the AppDomain as a container for data and code. The CLR allows multiple .NET applications to run in a single AppDomain.

Answer:   Applcation domain is shortly known as AppDomain. It can be considered as a Lightweight process which is both a container and boundary. The .NET runtime uses an AppDomain as a container for code and data, just like the operating system uses a process as a container for code and data. As the operating system uses a process to isolate misbehaving code, the .NET runtime uses an AppDomain to isolate code inside of a secure boundary.

The CLR can allow the multiple .Net applications to be run in a single AppDomain.

The CLR isolates each application domain from all other application domains and prevents the configuration, security, or stability of a running .NET applications from affecting other applications.An AppDomain can be destroyed without effecting the other Appdomains in the process.