Age? Maturity? Experience?

What does it really mean to "Grow up"?
Does it mean that if you are older you are wiser?
Does it mean that if you are more mature that everybody else you are better?

Does it mean that if you are more experienced you have the right to step on others?
or

Does it mean that if you are responsible enough to know what should be done, even if you act

childish. Responsible in a way where you work your way slow but surely, in manner where
you don't boast to others what you are and what you have done, but to keep it to yourself and

know what is the better solution and act upon it. Growing up is something that must be

understood and is different with each person.