The bicep curl is a popular strength training exercise that primarily targets the biceps brachii muscle in the upper arm. It involves lifting a weight, typically a dumbbell or barbell, by bending the elbow while keeping the upper arm stationary. This movement helps to build muscle strength and size in the arms. To perform a bicep curl, stand with your feet shoulder-width apart, holding a weight in each hand. With your palms facing forward, curl the weights up towards your shoulders, then lower them back down in a controlled manner. Proper form is essential to avoid injury and maximize effectiveness.