The biceps are the pair of muscles on the front of the upper arm connecting the shoulder to the elbow. From an aesthetic point of view they are also very prominent: the ‘classic’ bodybuilder or strongman pose involves flexing the biceps. As such they are often used as a visual measure of strength (or even masculinity). Regardless of motive, it is desirable for a bodybuilder to have a pair of big and strong arms.
The biceps are a very small muscle compared to the rest of the body, and must be coaxed into growing by adding muscle to your entire frame. Biceps will not grow unless the rest of the body does; it takes around 20lbs of muscular weight for an extra inch on your arms. Therefore a bodybuilder wishing to build up their biceps should focus on adding overall muscle through a good workout plan and a high calorie, protein-rich nutritional base to support it.
The biceps are a small muscle (relative to the rest of the body) and do not need a particularly hard stimulus to grow. A mistake made by many trainers in an attempt to develop their biceps is to use many exercises and many sets and many repetitions for what is a small muscle; bicep are small and recover quickly, but are also susceptible to overtraining. Many bodybuilders use 20+ sets for arms when in reality, 2-4 is all most people need. Some people with stubborn biceps may need to use more but for the majority of bodybuilders, a few hard sets is all the stimulus their arms need.
Initially a bodybuilder should just stick with two bicep/forearm movements, or two bicep movements (try to pair a traditional curl with one that works the brachialis, such as hammer or reverse curls). Repetitions should be on the higher side (8-12); these movements should be done once a week on the day the bodybuilder trains the other pulling muscles (the back). Since most back exercises involve the biceps as well to a large degree, they will receive indirect work through these heavy compound movements (such as the deadlift and barbell row) and together with the bicep isolation exercises they should have more than enough stimulus.
Lastly, the biceps aren’t the only muscle on your arm. Two-thirds of arm mass is actually made up by the triceps, and these must also be developed to achieve an impressive arm size: don’t neglect your dips, close grip benches, skull crushers or pushdowns!