Sams Teach Yourself Visual Studio® .NET 2003 in 21 Days

The .NET Framework Class Library

The second most important piece of the .NET Framework is the .NET Framework class library (FCL). As you've seen, the common language runtime handles the dirty work of actually running the code you write. But to write the code, you need a foundation of available classes to access the resources of the operating system, database server, or file server. The FCL is made up of a hierarchy of namespaces that expose classes, structures, interfaces, enumerations, and delegates that give you access to these resources.

The namespaces are logically defined by functionality. For example, the System.Data namespace contains all the functionality available to accessing databases. This namespace is further broken down into System.Data.SqlClient ...