I asked the first question wrong, so let me rephrase it. I haven't had a baby, I'm normal weight for my age and height, skinny but I can't seem to get abs. No matter how many ab exercises I do my stomach won't tighten. Its flat, but I can grab some fat. What can I do to make it firm?

Have you just had a baby or lost a good amount of weight?

I asked the first question wrong, so let me rephrase it. I haven't had a baby, I'm normal weight for my age and height, skinny but I can't seem to get abs. No matter how many ab exercises I do my stomach won't tighten. Its flat, but I can grab some fat. What can I do to make it firm?
Abdominals exercises will only make the walls of your abs stronger but it doesn' actually flatten your stomach. Best way to flatten your stomach is to do cardio exercises, such as running, joing group exrcise in a gym, using cardiovascular machines. Though having a strong abdominals is crucial to last in a cardiovascular excercises.