What is Future in Flutter/Dart?

• A Future is used to represent a potential value, or error, that will be available at some time in the future. Receivers of a Future can register callbacks that handle the value or error once it is available. For example:

	Future<int> future = getFuture();
	future.then((value) => handleValue(value))
	      .catchError((error) => handleError(error));

• If a future doesn’t produce a usable value, then the future’s type is Future<void>.
• A future represents the result of an asynchronous operation, and can have two states:
  1. Uncompleted When you call an asynchronous function, it returns an uncompleted future. That future is waiting for the function’s asynchronous operation to finish or to throw an error.
  2. Completed If the asynchronous operation succeeds, the future completes with a value. Otherwise it completes with an error.