title: Lambda Expression use case and connection with Functional Interface
body: <p>I am currently learning about Lambda expressions in Java. As per my understanding it is a block of code that we can pass around so that it can be executed later. But I cannot think of examples when we want to execute the code later.</p>
  
  <p>What are various scenarios where this is useful? Also what is the connection between Lambda Expression and Functional interface?</p>