Punctuation: It is the art of using correctly the various marks in writing. The correct use of these stops and marks helps the reader to understand the passage exactly as it is meant by the writer. But the wrong use of either changes the very sense of the passage or makes it quiet meaningless; as,

1. "The patient," said the doctor, "has gone mad."
2. The patient said, "The doctor has gone mad."
3."The patient said, "The doctor has, "gone mad."

You can see that the first sentence given above means one thing; the second quiet another; and the third, nothing at all. And it is all due to their "PUNCTUATION".