Dynamic Keyword

dynamic is a type introduced in C# 2010, making a variable as dynamic type, skip compile time checking for that variable, it allows any operation / call to write at compile time.
If written code not get validated at run-time then at run time it throw error.

dynamic keyword is an example of Late Binding
Early Binding : Compile time checking

Late Binding : Run time checking not compile time

dynamic converts early binding to late binding

Source Code: 
Below code compiled successfully

    class Program

    {

        static void Main(string[] args)

        {

            //Example1 allowing mathematical operation on string at compile time

            dynamic str = "hello";

            str++;

            //Example2 allowing Update() method call that does not exist, at compile time

            dynamic objStudent = new student();

            objStudent.Update();

        }

    }

    class student

    {

        public int RollNo { get; set; }

        public string Name { get; set; }

        public void Add()

        {

        }

    }

Errors at run-time
Error 1

Error 2