Class Library are collections of predefine classes . these classes can be use by a programmer when develop a application which increase the functionality of program. class library are collection of common classes which mostly used by programmers.

In object-oriented programming , a class library is a collection of prewritten class es or coded templates, any of which can be specified and used by a programmer when developing an application program. The programmer specifies which classes are being used and furnishes data that instantiate s each class as an object that can be called when the program is executed. Access to and use of a class library greatly simplifies the job of the programmer since standard, pretested code is available that the programmer doesn't have to write.A class library is analogous to a subroutine library in earlier, procedural programming.

class library is nothing but collection of pre defined classes.

A Class 'Library' is a set of reusable classes meant for providing a specif functionality that can be readily used by the application.

class library is nothing but collection of pre-defined classes and function which can be consumed by programmer for execution of Application