A cramp, also known as a spasm, is an involuntary contraction of a muscle that can cause sudden pain and discomfort. These contractions can occur in various muscles, including those in the legs, arms, or abdomen. Cramping can happen during physical activity, at rest, or even during sleep, and may last from a few seconds to several minutes. Common causes of cramps include dehydration, overexertion, and electrolyte imbalances, particularly involving minerals like sodium, potassium, and calcium. While most cramps are harmless and resolve on their own, persistent or severe cramps may require medical attention to rule out underlying conditions.