Object terminology in the real world

Consider the following three objects. They are cars, or, to put it more geekily, they are instances of the class Car.

Even though they are all instances of the class Car, you can see that one is a red four door, one is a red two door and the third one is a blue four door. Or, to put it more geekily, their properties have different values.

The value of the Color property is red
The value of the Number-of-Doors property is 4
The value of the Color property is red
The value of the Number-of-Doors property is 2.
The value of the Color property is blue.
The value of the Number-of-Doors property is 4.

Since they are all instances of the same class, each car has the same properties. However, they are not identical because those properties have different values.

The distinction between classes, objects and properties can be confusing. Thinking of parts of speech may help. Objects are nouns -- a car, a person, a bicycle, a chair, a business organization, etc. Properties and their values are like adjectives -- they describe objects. For example, your properties and their values describe you -- your height, weight, age, sex, whether or not you wear glasses, etc.

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