This document discusses the study of joints (arthrology). It defines joints and classifies them based on structure and function. There are three main types of joints: synarthroses (immovable), amphiarthroses (slightly movable), and diarthroses (freely movable synovial joints). Synovial joints have the most mobility and contain synovial fluid within a joint cavity. Synovial joints are further classified based on the shape of the articular surfaces and the number and plane of movements they allow. Common examples of each joint type are provided.