Singleton Design Pattern

Go through this link, you will have better understanding of singleton pattern

http://en.wikipedia.org/wiki/Singleton_pattern#C.23

Some differences between Singletons and Static classes are...

* Singletons can implement interfaces

* You cannot pass a static class as a parameter to a method, this can be done with a Singleton

* A Singleton is a normal class that is instantiated just once, a static class is never instantiated


UPDATE
As a side note, I usually tend not to use either of these. Instead I use my DI container (Ninject, StructureMap, ...) to supply me with a singleton of the required type when needed.

Singleton Pattern is a creational pattern and is all about making sure we have only one instance (maximum) of a class at any given point in time.

It just needs a private constructor so that none of the external instances can directly create an instance of the singleton class under consideration. This Singleton class needs to expose one public method eg: GetInstance, which intenally calls the private constuctor only if there is no preexisting instance of the class. Lock statements can be used in the implementation to avoid any hassles of multi-threaded access to the Singleton.