What is application domain ?

The application Domain is used to isolate an application from other applications. One process has its own virtual memory and does not over lap the other process's virtual memory; due to this one process can not crash the other process. As a result any problem or error in one process does not affect the other process. In .Net they went one step ahead introducing application domains. In application domain multiple applications can run in same process with out influencing each other. If one of the application domains throws error it does not affect the other application domains.