Full Name:
abstract

Short Name:
abstract

Type of Entity:
C#

Abstract:
The abstract modifier can be used with classes, methods, properties, indexers, and events. Use the abstract modifier in a class declaration to indicate that a class is intended only to be a base class of other classes. Members marked as abstract, or included in an abstract class, must be implemented by classes that derive from the abstract class.

MSDN Source URL:
http://msdn2.microsoft.com/sf985hc5.aspx