Guillain-Barré syndrome is an autoimmune disorder that causes the immune system to damage nerve cells, resulting in muscle weakness and sometimes paralysis. It is usually preceded by a bacterial or viral infection. The main symptoms are rapidly progressive muscle weakness, numbness, and tingling or pain in the legs and arms. Diagnosis involves clinical evaluation, neurological tests, and examination of cerebrospinal fluid. Treatment focuses on supportive care and immunotherapy such as intravenous immunoglobulin or plasmapheresis. Most patients recover fully but some have permanent nerve damage, and 5-10% of cases are fatal due to respiratory failure or cardiac complications.