Inlining is an attempt to remove the runtime overhead of lambda functions by moving (or inlining) the higher-order function and its lambda argument body to the call-site. By using this approach, no anonymous classes and function reference objects will be created during runtime. An inline function, therefore, is a function whose body and it’s lambda argument’s body will be inlined to the call-site at compile time. Inlining has its own set of rules and restrictions due to the nature of its approach, and we will discuss them later.