Normal vs. Descriptive Dialogue

1. A normal dialogue would go something like this:

"Hi Tony," said Katy.

"Hey," Tony answered.

"What's wrong?" Katy asked.

"Nothing," Tony said.

"Really? You don't act like nothing's wrong."

2. A descriptive dialogue would set the scene, advance action and give insight into the characters' lives: 

"Hi Tony."

Tony looked down at his shoe, dug in his toe, and pushed around a pile of dust. "Hey," he replied.

Katy could tell something was wrong.

Instead of telling the reader, a good writer will describe the scene in a way that conjures the image of a whining little boy. For example, 

He stood in the doorway with his hands balled into little fists at his sides. His red, tear-rimmed eyes glared up at his mother. "But I don't want to go to sleep yet."

3. A Thought in Dialogue or indirect dialogue, depicting the characters' thoughts is always italicized. 

"Hi Tony."

Tony looked down at his shoe, dug in his toe, and pushed around a pile of dust. "Hey," he replied.

Katy braced herself. Something was wrong.

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