What data or result does an asynchronously executed operation return?

An asynchronous operation in Flutter (and in other languages) returns a result that becomes available in the future, after the task completes. Usually, this is an object of type Future<T>, where T is the type of the returned data.

For example, when loading data from the network, a function returns a Future<String>, which eventually contains the received text.

Example:

Future<String> fetchData() async {
  // simulate delay
  await Future.delayed(Duration(seconds: 2));
  return "Data loaded";
}

void main() async {
  String result = await fetchData();
  print(result); // Will print: Data loaded
}

Thus, an asynchronous operation returns a promise (Future) that is later resolved with a result or an error.