Bicep curls are a popular strength training exercise that primarily targets the biceps, the muscles located at the front of the upper arm. To perform a bicep curl, you typically hold a dumbbell or a barbell in each hand with your arms fully extended at your sides. As you lift the weights, you bend your elbows and bring the weights toward your shoulders, then lower them back to the starting position. This exercise can be done standing or seated and is often included in workout routines to build arm strength and improve muscle tone. Bicep curls can be modified using different weights or resistance bands to suit various fitness levels.