Meningitis is an inflammation of the meninges, the protective membranes covering the brain and spinal cord. It is usually caused by a viral or bacterial infection of the cerebrospinal fluid surrounding the brain and spinal cord. Meningitis can be life-threatening due to the inflammation's proximity to the brain and spinal cord, making it a medical emergency. Common symptoms include severe headache, stiff neck, fever, nausea, and altered mental status. Diagnosis involves examination, history, and cerebrospinal fluid analysis. Treatment focuses on antibiotics for bacterial meningitis and managing symptoms such as seizures and swelling.