Introduction - If you have any usage issues, please Google them yourself
To run a. NET runtime host application, or when, OS will first establish a process, then loaded in the process CLR (this is usually loaded by calling _CorExeMain or _CorBindToRuntimeEx method to achieve), when loading the CLR creates a default AppDomain, it is the CLR running unit, the program' s Main method is where the implementation of the default AppDomain is the only and can not be unloaded, and when the process of elimination, the default AppDomain will disappear.