Abstract classes cannot be instantiated, they can only be inherited.
Abstract classes can have both abstract and non-abstract methods.
An abstract method must be implemented in the subclass; otherwise, the subclass must also be declared as an abstract class.
Abstract classes can have member attributes and member methods.
Abstract classes can be inherited, enabling subclasses to inherit the properties and methods of the parent class, and polymorphism can be achieved by overriding methods.
Abstract classes can be used to define common methods and properties for subclasses to inherit and implement.
