A fundamental arm-building exercise that targets the biceps brachii, responsible for elbow flexion and forearm rotation. Typically performed with dumbbells, a barbell, or cables, the curl isolates the biceps for focused strength and hypertrophy. It's a staple in any arm routine and great for both beginners and advanced lifters. Remember to keep your elbows tucked and avoid using momentum to ensure maximum bicep activation and reduce strain on the joints.