in c#, how do i decide when to make a class(es) a DLL or when to implement it as just an exe? im a little vague on the area. in my mind, i would make a dll that contained a bunch of similar classes or classes that associate with one another and implement the exe file as just a interface class for the DLL (ie, like in say Java, have some Greeter class, and have a seperate GreeterTest class to instantiate the Greeter class) is this the right train of thought or am i completely off?

Dlls are made to kind of splitting the whole program into small files so that the whole of program doesnt get loaded and crash the memory. So when a dll is called only a part of the program is loaded into the memory