Can you explain what is meant by an interface in object-oriented programming?

In object-oriented programming, an interface is an abstract type that defines a set of methods that a class must implement, but does not contain their specific implementation. The interface sets a contract that guarantees objects implementing this interface will have a certain set of functions.

In Dart (the language used in Flutter), interfaces are implemented through abstract classes or simply through classes that other classes can implement using the implements keyword.

Example:

abstract class Animal {
  void makeSound();
}

class Dog implements Animal {
  @override
  void makeSound() {
    print('Woof');
  }
}

Here, Animal is an interface with the method makeSound(), and the class Dog implements this interface, providing a specific implementation of the method.