What is the difference between a first and third person narrative?

First person is written when the author is in the story. They use the Words; I, me and my etc. e.g. " Iopened the door with my old keys."

Second person is written when the author is putting the reader into the story. The author uses Words like; you and your etc. e.g. "You opened the door withyour old keys."

Third person is written when the author wants to write like they and the reader are 'backstage' and are watching the scene. They use the Words; they, he and she etc. e.g. "They opened the door with her old keys."

Each type can be used to advantage for different effects on the story.