Abstract class

1. class that is declared using “abstract” keyword; 
2. may or may not include abstract methods ( has no body)and concrete methods (methods with body) ;
3. we can  not allowed to create object of Abstract class,
4. An abstract class has no use until unless it is extended by some other class ,logic behind structuring inheritance property for project[animal-dog,cow].
5. it provides partial abstraction only,100% abstraction - interface.

See --

Interface , 

abstraction VS interface