Generics are the most powerful feature of C# 2.0. Generics allow you to define type-safe data structures, without committing to actual data types. Instead of writing a function or a class for a particular type, it can be written generally to use any type. When an instance of the generic class is instantiated, the type is specified.
Eg. You might create a generic sorting class and when you create an instance of this, the type of entity it sorts is specified. One instance might sort ints, another doubles, and another payroll records.
What Generics Cannot Do
You cannot define generic Web services. That is, Web methods that use generic type parameters. The reason is that none of the Web service standards support generic services.
You also cannot use generic types on a serviced component. The reason is that generics do not meet COM visibility requirements, which are required for serviced components (just like you could not use C++ templates in COM or COM+).
