There are a number of ways to work your core however you may not think that you are working your core when I tell you what they are.
A lot of people work their core by doing sit ups and back extenders.
But those muscles were not intended to be isolated like that, in fact, no muscles were intended to be isolated.
The core muscles of your back and abdomen were intended by nature to be used in support of other muscles.
They are intended to help you maintain your balance, your posture and, in the case of your abdomen, to keep your insides from falling out.
Consequently, the best exercises to do work multiple muscle groups at the same time.
Now, you may think that the dead lift is for your legs and you'd be right.
However, if you think about it, you will realize that it also works the forearms the shoulders and, of course your back and abs as well.
The clean and jerk is one of my favorite exercises because it works everything, legs, arms, shoulders and also your core.
Just think how your back and abdomen must be involved in assisting your arms as they forcefully jerk the bar bell to your chest.
Then think about how they must help stabilize you and maintain your balance as you hold the weight over head.
Other lifts include the squat, military press, lunge, straight legged dead lift and others.
If you want to concentrate on your abs you can do renegade rows.
Again, looks can be deceiving, you would think that you are working your shoulders but you are actually focusing on your abs.