what is the difference between abstract class and concerete class in c++ 2011

[Vuhelper]

Abstract classess are those classess whose objects can't be initiated. These classess are used to play the role ob Base Class. Where as Concrete classess are those classess whose objects can be instantiated. For example we have two classess Shape and Triangle. As you know there is inheritance relationship between these two classess. Triangle is the derived class of Shape. Also, you know Shape is an abstract class whose purpose here is to provide Inheritance relationship.No need to have objects for this class, so we declare this class as an Abstract class, it means its objects can't be instantiated.