BCL (Base Class Library) vs FCL (Framework Class Library)

Question

What\'s the difference between the two? Can we use them interchangeably?

Answer 1

The Base Class Library (BCL) is the core set of classes that serve as the basic API of the Common Language Runtime. The classes in mscorlib.dll and some of the classes in System.dll and System.core.dll are considered to be a part of the BCL. It includes the classes in namespaces like System , System.Diagnostics , System.Globalization, System.Resources , System.Text , System.Runtime.Serialization and System.Data etc.

The Framework Class Library (FCL) is a superset of the BCL classes and refers to the entire class library that ships with .NET Framework. It includes an expanded set of libraries, including Windows Forms, ADO.NET, ASP.NET, Language Integrated Query, Windows Presentation Foundation, Windows Communication Foundation among others.

So there are differences and you must not use those interchangeably.