The Framework Class Library (FCL) is a standard library

Standard library

A standard library for a programming language is the library that is conventionally made available in every implementation of that language. In some cases, the library is described directly in the programming language specification; in other cases, the contents of the standard library are...

 and one of two core components of Microsoft .NET Framework

.NET Framework

The .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...

. The FCL is a collection of thousands of reusable classes (within hundreds of namespaces), interfaces and value types. The Base Class Library

Base Class Library

The Base Class Library is a standard library available to all languages using the .NET Framework. .NET includes the BCL in order to encapsulate a large number of common functions, such as file reading and writing, graphic rendering, database interaction, and XML document manipulation, which makes...

is a part of FCL and provides the most fundamental functionality, which includes classes in namespaces System, System.CodeDom, System.Collections, System.Diagnostics, System.Globalization, System.IO, System.Resources and System.Text.

External links

• .NET Framework Developer Center. Microsoft Developer Network (MSDN).
• .NET Framework 3.5 namespaces