Lambda Calculus is a big change in mathematical world which has been introduced in 1930. Because of benefits of Lambda Calculus slowly this concept started being used in the programming world. “LISP” is the first programming which used Lambda Expression. Simultaneously, some other languages are already using lambda expressions such as : C, C++, C# .Net, C Objective, Python, Ruby and obviously Java as well. However, our topic of discussion is 'Lambda Expression in Java'. Lambda Expression in Java is one of the crucial feature within the new features introduced in Java 8. Let's start discussing 'Lambda Expression in Java' and related concepts step by step. Why we use Lambda Expression in Java? The primary Objective of introducing Lambda Expression is to promote