Promises
Promises are a programming pattern and abstraction in asynchronous programming that represent a value that may be available now, in the future, or never. They provide a cleaner alternative to callback-based asynchronous code by allowing developers to chain operations and handle success or failure states more elegantly. In many languages, Promises are implemented as objects with methods like `then`, `catch`, and `finally` to manage asynchronous results.
Developers should learn Promises to write more maintainable and readable asynchronous code, especially in web development for handling API calls, file I/O, or timers. They are essential in JavaScript for avoiding 'callback hell' and are widely used in modern frameworks like React and Node.js. Promises also serve as the foundation for more advanced patterns like async/await, making them a critical skill for backend and frontend development.