The armbar, also known as 'juji gatame,' is a highly versatile joint lock that hyperextends the opponent's elbow. It can be applied from numerous positions, but isolating the opponent's arm is crucial. This is typically achieved by pinning the arm to the floor or bringing it between your legs using grips. Trap one leg high on their shoulder to prevent them from rolling, while controlling their hand. Use your body as leverage, pulling down with your legs and arms as you extend their elbow to its maximum point. This movement, combined with a forward drive, creates a natural hyperextension, forcing a submission. The arm bar may be performed from various positions.