A joint is the part of the body where two or more bones meet to allow movement. Every bone in the body, except for the hyoid bone in the throat, meets up with at least one other bone at a joint. Joints are described by how much movement they allow, and there are three broad classes of joints: immovable, slightly movable, and freely movable. The three types of joints are synarthrosis (immovable), amphiarthrosis (slightly moveable), and diarthrosis (freely moveable) .

The shape of a joint depends on its function, and joints are also known as articulations. Generally speaking, the more movement that is possible through a joint, the higher the risk of injury, because greater range of movement reduces the strength of the joint. Strong ligaments surround the joint to give support and limit the joints movement, and tendons on each side of a joint attach to muscles that control movement of the joint.

There are many types of joints, including joints that don’t move in adults, such as the suture joints in the skull, and joints that may move a little, such as the vertebrae. Examples of mobile joints include ball-and-socket joints, hinge joints, pivot joints, and gliding joints. The different types of joints are classified based on their function and composition.

In summary, a joint is the part of the body where two or more bones meet to allow movement, and there are different types of joints that allow different ranges of motion.