Abstract

A Java programming language keyword used with formally unfinished class and method , it is used to specify that a class is not to be instantiated, but rather inherited by other classes. An abstract class provides a base for someone to extend an actual class. An abstact class is deliberatesly missing some or all of the method bodies. An abstract class can have abstract methods that are not implemented in the abstract class, but in subclasses. You can't use new on abstract classes, but you can use abstract references, which always point to some extension of the abstract class.

A abstract method is a method which has no implementation, means an abstract method is deliberately missing its method body.