Promises in JavaScript are a way to handle asynchronous operations. Asynchronous operations are ones where the outcome of the operation is not immediately known, and the code must continue to execute while waiting for the outcome. Examples of asynchronous operations in JavaScript are network requests, file system operations, and database queries.

With Promises, you define a function that performs the operation, and the function returns an object (the Promise) that represents the eventual outcome of the operation. The Promise has two possible outcomes: it can either be resolved (meaning the operation succeeded and returned a value), or rejected (meaning the operation failed and returned an error).

Promises allow you to write cleaner and more maintainable code, since you don't have to rely on callback functions to handle the outcome of asynchronous operations. Instead, you can write code that reads like synchronous code, using a "then" method to specify what should happen when the Promise is resolved, and a "catch" method to handle any errors that occur.

In addition to "then" and "catch", Promises also have other methods like "finally" (which is called regardless of whether the Promise is resolved or rejected), and "all" (which allows you to run multiple Promises in parallel and wait for all of them to complete).

Promises are a fundamental concept in JavaScript, and are often used to handle asynchronous operations in a more organized and reliable way.

By definition, a promise is an object that represents a value that may not be available yet, but will eventually be.

1. Pending: The initial state before the promise is resolved or rejected.

2. Fulfilled: When the promise is resolved and a value is available.

3. Rejected: When the promise is unable to resolve and an error message is returned.

Promises provide a consistent interface for handling asynchronous operations, making it easy to write code that is clear and concise. When working with promises, we typically attach a .then() method to the promise which will be invoked once the operation is complete. This .then() method can then be used to specify what happens when the promise is resolved.

Another important feature of promises is their ability to chain multiple asynchronous operations together using the .then() method. This allows us to create a series of operations that rely on each other, without having to nest multiple callbacks within each other.

Overall, promises are a powerful tool in JavaScript that can help you manage complex asynchronous operations in a structured and reliable way.