There are two main ways to classify joints in the human body. Structural classification divides joints into three categories - fibrous, cartilaginous, and synovial - based on how the bones connect and whether a space exists between them. Functional classification also has three categories - synarthrosis, amphiarthrosis, and diarthrosis - and considers the degree of movement permitted at each joint. Synovial joints allow the most movement as diarthrosis joints, while fibrous joints permit the least movement and are mostly synarthrosis joints.