Closures are a magical part of the browser's JavaScript engine that remembers the variable environment of the Execution Context in which its connected function was born. It can easily recall the variables of the surrounding environment within which it got created.
crackjs-medium/closures.js at main · justmrkhan/crackjs-medium
Jonas’ Course made the foundation of my understanding of Closures.
Reference for the Multiplier Example.
Interview Question — Tricky Closure references.
7 Interview Questions on JavaScript Closures. Can You Answer Them?
Closures Explained in 100 Seconds // Tricky JavaScript Interview Prep
Are those hidden variables stored in the Heap Memory?
Wikipedia Reference.
Helped in understanding the concept
Javascript interview | Closure
The Beginner's Guide to JavaScript Closure and Its Usages