Multiple sclerosis is an autoimmune disease in which immune cells attack and destroy the protective myelin sheaths that surround nerve fibres, leading to neurological disturbances. After spinal cord ...

Clay Halton was a Business Editor at Investopedia and has been working in the finance publishing field for more than five years. He also writes and edits personal finance content, with a focus on ...

PLUS, for a limited time, get bonus gifts and issues with all Nat Geo subscriptions.