Final answer:
Dips primarily target the triceps muscles on the back of the upper arm, which are responsible for extending the forearm at the elbow joint.
Step-by-step explanation:
The exercise known as dips primarily works the triceps muscles. When performing a dip, you are effectively pushing your body up and away from a set of parallel bars or a similar setup, which activates and engages the triceps. The triceps are the muscles on the back of the upper arm, and they are responsible for the extension of the elbow joint. This means that they help to straighten the arm from a bent position.
Although dips can engage multiple muscle groups, including the chest and shoulders, the primary target is the triceps. The triceps brachii, specifically, is the muscle that enables the forearm to extend, and during dips, this muscle is worked extensively.