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Action "Encapsulates a method that has a single parameter and does not return a value." ~ MSDN , you don't need to create your own custom delegate to pass a method as a parameter, you can use Action<T> instead. The compiler will figure out the proper types. Action is a type of delegate and takes 0 till 16 parameter with a void value return. This means that the encapsulated method must have one parameter that is passed to it by value, and it must not return a value.

When you are working with delegate (a type that encapsulate a method ), maybe we define something like this

1.     public class DelegateClass
2.     {
3.         public delegate string DelegateDoSomething();
4.  
5.         public string GetSomething()
6.         {
7.             throw new NotImplementedException();
8.         }
9.  
10.         public static void Presenting()
11.         {
12.             DelegateClass delegateClass = new DelegateClass();
13.             DelegateDoSomething delegateDoSomething = new DelegateDoSomething(delegateClass.GetSomething);
14.         }
15.     }

 

By defining the DelegateDoSomething as a delegate we passed the GetSomething() as a parameter,  With Action<T> we can pass method as a parameter easier, take a look this

1.     public class ActionClass
2.     {
3.         public static void Presenting()
4.         {
5.             Action<string> DoSomething = delegate
6.             {
7.                 throw new NotImplementedException();
8.             };
9.         }
10.     }

 

you can use the Action with anonymous method, take a look at the example

1.         public static void AnotherPresenting()
2.         {
3.             Action<int> ADelegate;
4.             ADelegate = delegate(int a)
5.                 {
6.                     throw new NotImplementedException();
7.                 };
8.             ADelegate(1);
9.         }

You can also define Action with lambda expression, look at the sample

1.         public static void AnotherPresenting2()
2.         {
3.             Action<int> AnAnonymous;
4.             AnAnonymous = a => Console.Write(2);
5.             AnAnonymous(2);
6.         }

 

 

Hope you found useful, cheers! More information about Action<T>

1. http://msdn.microsoft.com/en-us/library/018hxwa8.aspx
2. http://www.c-sharpcorner.com/UploadFile/dhananjaycoder/what-is-action-in-c-sharp/
3. http://blogs.msdn.com/b/brunoterkaly/archive/2012/03/02/c-delegates-actions-lambdas-keeping-it-super-simple.aspx