All collection classes in the .NET Framework implement some combination of the collection interfaces. These interfaces declare the operations to be performed generically on various types of collections. Figure 21.1 lists some of the interfaces of the .NET Framework collections. All the interfaces in Fig. 21.1 are declared in namespace
System.Collections and have generic analogs in namespace
System.Collections.Generic. Implementations of these interfaces are provided within the framework. Programmers may also provide implementations specific to their own requirements.