If fully completed all functionality and ready to provide service is called concrete class Real Time example :A complete Building

A concrete class is used to define a useful object that can be instantiated as an automatic variable on the program stack. The implementation of a concrete class is defined. The concrete class is not intended to be a base class and no attempt to minimize dependency on other classes in the implementation or behavior of the class..

Concrete class 1. we can create instance as well as we can inherit. 2. No method should be abstract. 3. In application class hierarchy, concrete class need not be in the first level.

Concrete class is nothing but normal class, we can use as a base class or may not.Not compulsory, it can't contain abstract methods.we can create object and work with this class.

A concrete class is used to define a useful object that can be instantiated as an automatic variable on the program stack. The implementation of a concrete class is defined. The concrete class is not intended to be a base class and no attempt to minimize dependency on other classes in the implementation or behavior of the class..