Turbo Pascal: object oriented programming guide

 Object-oriented programming is a method of programming that closely mimics the way all of us get things done. It is a natural evolution from earlier innovations to programming language design: It is more structured than previous attempts at structured programming; and it is more modular and abstract than previous attempts at data abstraction and detail hiding. Three main properties characterize an object-oriented programming language.
 
• Encapsulation : Combining a record with the procedures and functions that manipulate it to form a new data type: an object.
• Inheritance: Defining an object and then using it to build a hierarchy of descendant objects, with each descendant inheriting access to all its ancestors' code and data.
• Polymorphism: Giving an action one name that is shared up and down an object hierarchy, with each object in the hierarchy implementing the action in a way appropriate to itself