Class Library:The .Net Framework class library is a collection of reusable types that tightlyintegrate with the common language runtime. The class library is object oriented,providing types from which you own manage code can derive functionaly.This not onlymakes the .NET Framework type easy to use, but also reduces the time associatedwith learning new features of .Net Framework. In addition, third partycomponents can integrate seamlessly with classes in the .Net Framework.
Including task such as
* String Management
*And file access
The .net Framework class library is a library of classes,and, interfaces, and values, and types that are included in the Microsoft.Netframe work SDK. This library provides access to system functionality and isdesigned to be the foundation on which .Net Framework applications, components,and controls are built.