Neuromyelitis optica also known as Devic's syndrome is a rare autoimmune disorder that predominantly targets the optic nerves and the spinal cord. It is a debilitating disorder that damages a person's health. Initially it was considered as a variant of multiple sclerosis (MS). But, in 2004, a water channel protein associated antibody was found to be responsible for the disease. This helped in distinguishing the disease from multiple sclerosis. Multiple molecular mechanisms like complement dependent cytotoxicity, antibody‑dependent cellular cytotoxicity etc. contribute to the disease. Certain environmental and genetic factors have been identified as risk factors of the disease. Initially, the disease was thought to affect only the optic nerves and the spinal cord. But certain regions of the brain have also been found to be attacked during the course of the disease. A small proportion of the patients have been found to be seronegative for the AQP4‑IgG. Recently, the term neuromyelitis optica spectrum disorder has been framed to include all the features of the disease. The disease remains incurable despite the availability of various treatment modalities. This review presents critical information obtained from prior studies regarding the disease and also raise several questions to understand the research gaps in this field.