What are joints?
A joint is the point where two or more bones come together. Joints can be fixed, such as those that hold together the rounded part of the skull, or they can allow movement, such as your knees and elbows. Straps of tough flexible material called ligament hold together the bones in a joint.
How do joints work?
The ends of most bones are covered with tough rubbery cartilage, which cushions them from impact as we move.
Many joints are lubricated with an oily liquid called synovial fluid so they can bend freely. Synovial fluid is held in a bladder between the layers of cartilage on the ends of the bone. These lubricated joints can move freely and without friction.
Pictures Credit: Google