Var and Dynamic keyword in C#

Var was introduced in C# 3.0 and dynamic was introduced in C# 4.0. When we define a variable as var that means we cannot change its data type after first initialization and data type checking at compile time. When we define a variable as dynamic that means we can change its data type for any number of times during program execution and data type checking at run time.

class vardynamic
    {
        public void show()
        {
            var a = "Hello var";
            dynamic b = “Hello dynamic”;
            Console.WriteLine("a: {0}", a);
            Console.WriteLine("b: {0}", b);
            //a = 10;
            //Console.WriteLine(a);
            b = 10;
            Console.WriteLine(b);
        }
    }

In above class, I have defined two variable a and b with var and dynamic respectively. Both the variables first initialized as string data type. If I uncomment two lines, program will give compile time error because variable a is first initialized as string that later changing to integer data type which is not possible. But b can be changed to string data type to integer data type because it is declared as dynamic.