Cost is what you give up to get something you want. Usually cost means money: a video game might cost $30, or a sandwich might cost $8. But cost isn't always measured in dollars.

Sometimes the cost is your time. Joining the soccer team costs you three afternoons per week. Learning to play piano well costs hundreds of hours of practice. When you choose to spend Saturday morning helping your neighbor rake leaves, the cost might be missing your favorite show.

Cost can also mean effort, comfort, or other things you value. Training for a marathon costs sweat and sore muscles. Standing up for a friend who's being teased might cost you popularity with certain classmates. Making the honor roll costs late nights studying instead of playing games.

People say something cost them dearly when the price was high and painful. They might ask “at what cost?” when questioning whether an achievement was worth what someone sacrificed to get it. Understanding cost helps you make decisions: is what you're getting worth what you're giving up? Sometimes the answer is yes, sometimes no.