What is a .NET application domain?

Question

In particular, what are the implications of running code in two different application domains?

How is data normally passed across the application domain boundary? I

Answer 1

Each application running within a process, AppDomain is also a light-weight process or we can say logical unit which having group of assemblies (this is a container which contain group of assemblies ) and this exist inside of the process at isolation level of same process, this allows to run multiple assemblies within same process and prevent them for direct access.

Running Dot Net Application Within AppDomain: Once any dot net application run, Operation system shell load CLR into a process and new AppDomain been created in the same process and load all the assemblies in the created AppDomain, now from the AppDomain code will get executed.

When to Custom AppDomain: We can create own AppDomain, now the thing is in which scenario we can create own AppDomain. Suppose run time we need to add or remove the assemblies without interruption the running application then we can create own AppDomain.