What is Action,Func delegate in C#

Action: 

Encapsulates a method that has no parameter or one parameter or more parameters and does not return a value, method return type should be void(c#) or Sub .... End Sub (vb.net).

E.g.

    class Program
    {

        static void Main(string[] args)

        {

            Action<int> action = new Action<int>(DoSomething);

            action.Invoke(1009);

        }

        static void DoSomething(int i)

        {

            Console.WriteLine(i);

        } 

    }

O/P:

1009

Func:

Encapsulates a method that has no parameters or one or parameters and returns a value of the type specified by the TResult parameter.

//Func delegate with one parameter and TResult

public delegate TResult Func<in T, out TResult>(T arg)

E.g.

   class Program

    {

        private static void Main(string[] args)

        {            

            Func<int, double> func = new Func<int, double>(CalcualteSomething);

            Console.WriteLine(func(5)); //Should Print 25

        }

  

        private static double CalcualteSomething(int i)

        {      

           return (double) i*2;

        }

    }