A literary device used to introduce background information about events, settings, characters etc. to the audience or readers. (Note: you cannot totally avoid exposition, but you should limit your use of it. It takes the reader away from the action of the story.)
Example: "Once upon a time, there were three bears. There was a Daddy Bear, who was very big, a Mama Bear, who was middle-sized, and a Baby Bear, who was very small. They all lived together in a little cottage in the middle of the woods. Their favorite breakfast was porridge. One morning, after they made their porridge, Daddy Bear said, 'Let's go for walk in the woods until it cools.' Mama Bear and Baby Bear liked the idea, so off they went. While they were away, a little girl named Goldilocks came walking through the forest and smelled the porridge..."
A rhetorical device in which two opposite ideas are put together in a sentence to achieve a contrasting effect.
Example: "It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity, it was the season of Light, it was the season of Darkness, it was the spring of hope, it was the winter of despair, we had everything before us, we had nothing before us, we were all going direct to Heaven, we were all going direct the other way." (from A tale of Two Cities by Charles Dickens)