Your core muscles brace your torso & spine. That's about 3 dozen muscles around your torso (both front and back).
Our core muscles are designed to assist the rest of the body.. as opposed to working in isolation (like crunches). So good "core exercises" also work other muscles groups (legs, chest, upper back). Good core exercises include squats, pushups, bent-over barbell rows, sprinting, etc.
By the way, the "core" of your core is your transversus abdominis muscle. It's activated by "bracing" your abs. It's good to do this whenever moving around, lifting, running, etc.
Interesting question. Why do you ask?
Edited by: CHERIMOOSE at: 12/1/2012 (09:25)