Muscle cramps are sudden, involuntary contractions of one or more muscles, often causing pain and discomfort. They can occur during physical activity, at rest, or even during sleep. Common causes include dehydration, overexertion, and imbalances in electrolytes like sodium, potassium, and calcium. These cramps can affect any muscle but are most frequently experienced in the legs, particularly the calf muscles. While they are usually harmless and resolve on their own, persistent or severe cramps may require medical attention to rule out underlying conditions or deficiencies related to nutrition or exercise.