It is the representation of conversation within a literary work....
For example: The Little Boy and the Old Man
by Shel Silverstein:
Said the little boy, “Sometimes I drop my spoon.” Said the little old man, “I do that too.”
The little boy whispered, “I wet my pants.”
“I do that too,” laughed the little old man.
Said the little boy, “I often cry.”
The old man nodded, “So do I.”
“But worst of all,” said the boy, “....
Dialogue is also known as casual conversation between two people or objects.
The principal or main character around which a literary work usually revolves
For example:In the movie The Little Mermaid, Ariel is the protagonist. Her conflict is that she is in love with a human and her father doesn't understand.