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Let's start with objects. An object is a
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computing unit organized around a collection of state
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or instance variables that define the state of
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the object. In addition, each object has associated
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with it a set operations or methods that
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operate on such state. So what that means
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is that operations and methods read and write
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instance variables. And in traditional object orientation, we say
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that operations are invoked by sending a message
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to the appropriate object, which is what we call
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normally a method implication. So now that we define
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what an object is, state variables, or attributes, and
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operations or methods, let's see what a class is.
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A class is basically a template. A blueprint, if
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you wish, from which new objects, which is what
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we call instances of the class can be created.
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And notice that the fact of having a blueprint for
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objects that allows us to create as many objects as
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we want can further reuse, and also contribute to make
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the code more readable, understandable,
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and therefore ultimately more maintainable.
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