Muscle is a type of tissue in the body that helps us move. It is made up of long, thin cells that can contract, or shorten, to create movement. There are three main types of muscle: skeletal muscle, which helps us move our bones; smooth muscle, which controls movements in our organs; and cardiac muscle, which makes the heart beat. When we exercise, our muscles get stronger and bigger. This happens because the muscle fibers repair themselves after being used, making them more resilient. Keeping our muscles healthy is important for overall fitness and helps us perform daily activities with ease.