Understanding JavaScript Closures: How Functions Remember Their Scope

Closures are a core JavaScript concept where an inner function retains access to variables from its parent function's scope, even after the parent has finished executing. This behavior stems from how JavaScript assigns a lexical scope to every function at the time it is created. Unlike regular function calls, which recreate variables fresh on each invocation, closures allow state to persist across multiple calls without relying on global variables. This makes closures valuable for building features like counters, caches, and event handlers with private state. They also provide encapsulation by keeping variables inaccessible from outside, controllable only through the functions that close over them.