What is the JavaScript event loop and how does it work?

JavaScript runs on a single call stack, but the runtime schedules async callbacks through queues. After current synchronous code completes, queued tasks are processed. Promises (microtasks) run before macrotasks like setTimeout callbacks, which explains many ordering surprises during debugging.

console.log('A');
setTimeout(() => console.log('B'), 0);
Promise.resolve().then(() => console.log('C'));
console.log('D');
// Output: A, D, C, B

Start simple: try this concept in a tiny project before moving to advanced tools.