Multiple sclerosis (MS) is the most common disabling neurologic condition in young adults and imposes high financial and quality of life costs on patients, their families, and society. Yet, developments in the battle against MS include new treatments to slow its progression and updated diagnostic criteria that can accelerate diagnosis and effective treatment. This article offers a review and update on the disease, focusing on risk factors and possible causes, symptoms, forms of MS, diagnostic criteria and tools, and the expanding array of approved treatments. It also reports on the skyrocketing cost of MS drugs, misdiagnosis, and special patient populations with MS.