Before getting into the specific ab routine that you should do if you want get solid abs we need to cover a few basics on actually seeing your abs and that means eating correctly. In a nut-shell what this means is eating a well-balanced small meal every three hours to keep your metabolism at top speed.
A diet rich in protein changes the insulin response in your body, which hastens the melting of fat, and visceral fat, that deep layer of fat, is easier for your body to burn than the subcutaneous fat under your skin (the fat that you can see and grab).
Besides the exercises listed below you should also make sure that you train your entire core. To build really great abs it's important to first understand what abs do. Their full name is 'rectus abdominis'. The 'rectus' bit, is Latin for 'straight, proper, upright'. Contrary to popular opinion, the abs' primary job is not to curl you up into a ball, but they work together with the back muscles to maintain correct posture and stabilize the spine.
These muscles are not just for show! So the best exercises for abs are ones that force your entire core to go into overdrive to support your spine. Some exercises that do this are squats and deadlifts. These exercises will train your entire core to work together to do what it is designed to do. At the same time they will also train a lot of other muscles (e.g. glutes and quads).
The list of abs exercises below is what you should do for 20 minutes after every hard work-out. It does not need to be a long workout and you should train on high intensity making it short and effective. You should do about 30 reps before moving onto the next exercise.
Doing a circuit using all the exercises listed below is something that should actually finish with the Plank hold so that you have reached the point of failure on your abs. There are countless ways to train your abs and probably the most effective way to get results is with isolating and focus.
Jackknife sit ups
Twisting sit ups
Static holds/plank hold
For more info on how to get 6 pack abs fast go to How To Get A Perfect Six-Pack Of Abs ASAP