Abdominal Exercises
Everybody has abdominals, but not everybody's show. This is because some people have more fat on this area of their body. The muscles can't show through the fat. Which is why some people may have strong abdominals but no six pack, and a skinny guy with weak abdominals does. We would recommend that if you really want your six pack, you should use a fat burner supplement. For example, we would recommend Transparent Labs Fat Burner. This is because it fights hunger cravings and targets body fat. However, it is important you combine this supplement with exercises that will help strengthen your abs, so here is a list;
Sit Ups
These are the best exercise for upper and middle abdominals (top 6 out of 8 cubes). You can hook your feet under something if you want, or you can have someone hold your feet for you. From having your back flat on the floor mat, quickly raise your body all the way up until your chest hits your knees. You can also do this for half reps very effectively. Don't try to lift yourself up with momentum or inertia of your body, let the muscles do the work. Hand position is very important in this exercise, you should keep your hands on your ears, not pressing against them, but just holding your hands there. You can accomplish this by pointing your elbows outwardly. Do not grab the back of your head, that puts too much strain on your neck and could cause injury.
Crunches
These are halfway sit ups that work your upper and middle abs. You should do these with your legs in the air (or have your feet flat on the floor), bent at the knees, don't cross them if you can. That will get your abs to grow unevenly like most bodybuilders. Hand position is the same as for sit ups. Once again, try to reach your knees, but you probably won't be able to do that.
Leg Raises
These can be done hanging from a bar or on that special leg-raise stand. This exercise works the bottom of your abs (the bottom 4 cubes). If your abs are weak, to these with your legs bent at the knees. If your abs are strong, do them with straight legs. And don't just stop at a right angle, go as high as you can. Try not to rock back and forth. Also, you can do this flat on the floor. Place your hands under your buttocks for some support and leverage. Then lift your legs almost up to a right angle, then bring them down.
Side Crunches
These exercises work the oblique's. Your back should still be on the floor, but now your legs should be lying on one side of your body, bent at the knees. After doing this exercise the same way as described in “sit ups,” flip your legs to the other side and do the same number of reps.
Pull Over
You can do this exercise either the way it is done for chest or lats, it doesn't matter. Either way serratus will get a work out. Pull over also strengthens your abs and obliques. Don't do pull over for stomach, just know that when you do it for your chest or lats, your midsection is working too.
Incline/Decline Sit Ups
Get on the bench and do sit ups or leg raises depending on which way your head is facing. That's it. Works abdominals.
Abdominal Wheel
First want to grab a pillow to put under your knees. If you don't have one, the skin will wear right off your knees, see, the exercise is performed with your knees on the ground. One hand on each side of the ab-wheel, keeping your arms locked straight out, eyes looking at the wheel, push the wheel out from you, keeping your lower back from sagging towards the floor. Just when your abs are about to graze the floor, simply pull yourself back upright using your abs (you have no choice but to use your abs to do it). Someone just beginning to train their abs won't be able to go clear down like that-they should go as far as they can and still be able to come back up. For advanced folks, try doing some from your toes instead of knees.
Links for Reference
For more advice, we would advise that you read this Men's Fitness article on how to work your abs to exhaustion.