Types of classes

1. General class: Class is a collection of fields, properties, methods and events, where a method is a collection of statements and an event is an action on the object.
2. Static class: Static classes are loaded automatically by the .NET Framework common language runtime (CLR) when the program or namespace containing the class is loaded.
3. Sealed class: A sealed class cannot be inherited.
4. Partial class: With the partial class it is possible to split the definition of a class or a struct, or an interface over two or more source files. Each source file contains a section of the class definition, and all parts are combined when the application is compiled.
5. Abstract class: A class with abstract method (method without body is called abstract method) is called abstract class.
6. Generic class: Generic classes encapsulate operations that are not specific to a particular data type. 

Note:Please refer other posts for more details on the above mentioned classes