In computer programming, a callback, also known as a "call-after" function, is any executable code that is passed as an argument to other code; that other code is expected to call back (execute) the argument at a given time.

How do you explain callbacks?

A "callback" is any function that is called by another function which takes the first function as a parameter. A lot of the time, a "callback" is a function that is called when something happens. That something can be called an "event" in programmer-speak.

Why do we use callbacks?

Callbacks are a great way to handle something after something else has been completed. By something here we mean a function execution. If we want to execute a function right after the return of some other function, then callbacks can be used. JavaScript functions have the type of Objects.