Warm ups are exercises done before physical activity to prevent injuries and improve performance. They involve joint mobility exercises to prepare muscles and joints, as well as activation games to get the entire body moving. Activation engages all body systems like cardiovascular, digestive, and musculoskeletal. Examples given include running in a circle, moving arms side to side, and partner exercises like back-to-back running. The summary emphasizes that warm ups prepare the body for exercise through joint and full body movement.