A stability ball, also known as a Swiss ball or exercise ball, is a large inflated rubber ball that is used for various exercises and stretches to improve balance, coordination, strength, and flexibility. It can be used in physical therapy, Pilates, yoga, and other fitness routines to engage the core muscles and promote proper body alignment while performing movements or exercises. The instability of the ball forces users to engage their stabilizer muscles to maintain balance, which leads to improved posture, strength, and overall body control.