OOP is an acronym for object-oriented programming which simply means that you are using an object-oriented language to create a program that contains one or more objects. On the other hand, OOD or object –oriented design is a design methodology used to plan object-oriented programs. OOD divides a problem into one or more objects. Anything that can be seen or touch is referred to as object. Every object has attributes and behaviours. The characteristics that describe the object are called attributes. It is also known as data or properties. The operations or actions that the object can either perform or have performed on it are called behaviours.

Another term in OOP is class. A class is a pattern or blueprint for creating an object. This contains all of the attributes and behaviour that describe the object. The object you create from a class is known as the instance of the class. Always remember that a class is not an object but an instance of the class is an object.

In an explanatory why composition you present an opinion. You explain clearly and directly why a particular idea should be accepted. For instance, you may want to explain why Manila is a pleasant city or why every passenger in a car should wear seat belt.

To find topics for explanatory why compositions, simply think about your own life. What issues do you feel strongly about? For instance, how do you feel about your school, your neighbourhood, or your town? How do you feel about TV, work-study programs, public transportation, or the draft? Choose a topic that is important to you. After you have chosen your topic, make notes for your composition. Think about why you feel the way you do. Plan to state your opinion in the introduction. Plan to support your opinion in the introduction. Plan to support your opinion with reasons or facts in the body of the composition. Plan to sum up your argument in the conclusion.