Joint types are classified based on their structure and function. The main categories include fibrous joints, cartilaginous joints, and synovial joints. Fibrous joints, like those found in the skull, are connected by dense connective tissue and allow little to no movement. Cartilaginous joints, such as the ones between the vertebrae, permit limited movement and are connected by cartilage. Synovial joints are the most common and movable type, featuring a fluid-filled cavity that reduces friction during movement. Examples include hinge joints like the elbow and ball-and-socket joints like the shoulder. Each joint type plays a crucial role in the body's overall mobility and stability.