What is a Class Library in .NET?

Class library is the another major entity of the .NET Framework. This library gives the program access to runtime environment. The class library consists of lots of prewritten code that all the applications created in .NET aware languages and Visual Studio .NET will use. The code for all the elements like forms, controls and the rest in VB .NET applications actually comes from the class library.

Code in class libraries may be shared & reused. One of the core . NET libraries is mscorlib.dll. .NET language compilers reference this library automatically as it contains core types. A class library, contains types, that may be used by external applications. A class library may be a DLL or an EXE. Note that the .NET class libraries, even though have a same extension as the old COM Win32 binaries, yet they are very different internally.