This article, which forms part of the life sciences series, examines the sensory systems of the body. Sensory organs may be categorised as general or special. Sensory systems enabling sight, hearing, smell and taste may be classified as special. Sensory systems enabling proprioception, touch, and thermal and pain perception may be classified as general. This article describes the anatomy and physiology of the sensory systems, examining structures associated with vision and hearing, equilibrium and sensation. Common disorders of vision and hearing are also considered, including glaucoma, cataract, age-related hearing impairment and conductive hearing impairment.