Exact use of Abstract class

Question

What is the exact use of an Abstract class? Is not possible to do the same things in an ordinary class as it is an an abstract class?

Answer 1

Regular classes require you to provide implementations for all methods.
Interfaces require you to not provide any implementations for all methods.

Abstract classes are the only type of class that allow you to both have methods that do contain an implementation, and have methods that do not provide an implementation, but require an inheriting class to provide one.

The fact that you are allowed to add methods without an implementation is the reason you cannot instantiate an abstract class: you can only instantiate something that has implementations for all its methods.