Do you remember the first time you learned about atoms in science class? The teacher probably drew a sketch on the chalkboard that looked like a model of the solar system: a big nucleus in the middle orbited by a tiny electron. Later you probably learned that atoms do not actually look like the drawing on the board, but the model your teacher showed you helped you to understand atoms. In economics, when studying markets, you begin by learning something that is somewhat unrealistic, but a simple model of perfect competition will help you to understand real-world conditions.