How do Promises help you work with things that take time to complete?

A Promise is an object representing the eventual completion (or failure) of an asynchronous operation and its resulting value. Promises provide a cleaner, more manageable way to handle async operations compared to callback patterns.

A Promise can be in one of three states: pending (initial state, neither fulfilled nor rejected), fulfilled (the operation completed successfully), or rejected (the operation failed). Once a promise is fulfilled or rejected, it's settled and its state cannot change.

Promises are created with the Promise constructor: new Promise((resolve, reject) => { ... }). You call resolve(value) when the operation succeeds or reject(error) when it fails.

Consuming promises uses .then() for success, .catch() for errors, and .finally() for cleanup. These methods return new promises, enabling chaining: fetch(url).then(res => res.json()).then(data => process(data)).catch(err => handleError(err))

Promise.all() waits for all promises to resolve (or any to reject). Promise.race() resolves/rejects with the first promise to settle. Promise.allSettled() waits for all to settle regardless of outcome. Promise.any() resolves with the first to fulfill.

Understanding promises is essential for working with modern JavaScript APIs, async/await (which is syntactic sugar over promises), and proper error handling in asynchronous code.