Lambda expression ( =>) is anonymous function without a declaration.It allow you to write a method in the same place where you required. It is a single line method which return a value. Advantages: 1. It reduce the line of codes. 2. Inline method , so fast in execution. 3.Does not require write function elsewhere. But complex definition increase reduce execution speed so lambda expressions are useful for small and simple methods Example: List All_Number = new List { 1,2,3,4,5,6,7,8,9,10 }; List Even_Number = All_Number.Where(n => n % 2 == 0).ToList(); foreach (int lt in Even_Number) { Console.WriteLine(lt); } Output will be: 2 4 6 8 10