Callbacks & Callback Hell

A function that returns immediately
A function passed as an argument to another function to be executed later
A callback function is a function passed as an argument to another function, which is intended to be executed after the first function completes. It's a fundamental concept in asynchronous JavaScript that enables: 1) Handling asynchronous operations like API calls, 2) Executing code after a task completes, 3) Event handling, 4) Higher-order function implementation. Callbacks are the foundation of asynchronous programming in JavaScript.
A function that only handles errors
A synchronous function call