Objects represent various things in a program, like a Square. This is called Abstraction. An object for a square in a math program would have a set of variables, length and width, that can only be accessed by functions inside the object. This is called Encapsulation. This concept reduces the chance of 'breaking' something when programming, as when done properly only the object itself can directly manipulate its variables, so debugging problems is easier. The next part of an object, functions, represent things that the object can do or ways to interact with it. In the case of the square object, a function called "area" would calculate the area of the square the object represents, using the contents of the length and width variables inside the object. Those variables may already contain the length and width of the square, in the case they did not, the area function might also take user input for the length and width of the square the object represents and then calculate the area based on the user input.

In the case a math program was intended to calculate the area of not only squares, but other shapes, such as a circle, "Inheritance" would be used.Inheritance is when an object is created based on another object, so therefore, it "inherits" all of its variables and functions. For example, an extension to the earlier square area calculation program would have a main object, called a polygon. In geometry, a polygon is basically a "closed shape", i.e a square, triangle, circle, cube, etc. All polygons can have their area calculated, just the method of achieving such is different. So, in our program, the polygon object would have length and width variables, and an area function. Since a polygon is not actually a shape, but a class of shapes, the area function would not do anything. When you want to create an object for a particular kind of polygon (i.e a triangle), you would use inheritance to create the object with all the properties of its "parent", the polygon object. You would then cite the actions the area function inherited would perform. This concept is called "Inheritance". It makes much more sense when dealing with large programs, where objects typically contain lots of lines of code, in which rewriting an object similar to another would be tedious and pointless, when Inheritance can be used to get the same properties and methods of the parent object.

Many programmers have a hard time deciding which programming language to use. In Object-Oriented Programming, the two big languages are Java and C++. Both are good languages for various things. Many people will try and tell you that one is good and the other is bad, though you should try both and decide for yourself which one you like more.