Joint structures are the connections between two or more bones in the body. They allow for movement and flexibility while providing stability. There are several types of joints, including hinge joints, which enable bending and straightening, and ball-and-socket joints, which allow for a wide range of motion. The main components of joint structures include cartilage, which cushions the bones, and synovial fluid, which lubricates the joint. Ligaments, tough bands of tissue, connect bones to each other, while tendons attach muscles to bones, facilitating movement. Understanding these structures is essential for maintaining joint health and preventing injuries.