Imagine trying to kick a ball without swinging your leg or trying to throw a ball with an arm that was as wiggly as a rope. Getting your body to move the way you want it to requires joints, bones, and muscles. If you didn't have joints, you couldn't bend your leg to kick a ball. If you didn't have bones, your arm would be as floppy as a rope. And without muscles, you couldn't move at all.
Together, your muscles, bones, and joints are referred to as your musculoskeletal system, and their job is to provide support and movement for your body.
The muscles, bones, and joints are attached to each other by different tissues. Ligaments are found at your joints, and their job is to hold bones together. Tendons are found at the ends of muscles, and their job is to connect muscles to bones.