A static class is a class which contains static members & static methods. This class can be accessed directly without creating an instance of class.
They cannot be instantiated.
They are sealed so no class can be derived from this class.
Example of Static Classes in .Net Framework are
ActivityDesignerPaint under System.Workflow.ComponentModel.Design
ThrowHelper
 n Lot more Check while using Framework using Ctrl+ ALT+J - Object Browser