This document provides an overview of orthosis, including definitions of splints and braces, classifications of orthosis, principles of splint design, materials used, prefabricated splints, and biomechanical principles. It also describes various upper and lower limb orthosis, such as figure of eight axilla wraps, gunslinger splints, airplane splints, hemi arm slings, elbow flexion harnesses, cockup splints, and more. The objectives, indications, and designs of different orthosis are discussed in detail.