Yes. Read especially third paragraph below. (Identifying mark)
"X" as a signature refers to a cross that is printed in lieu of an individual's signature. A signature is required to authenticate...
For people: Only if you have legal power of attorney for that person. For businesses: Only if you are officialy authorized by your company to sign on said persons behalf.
The age would be the age of majority. In most places that will be 18 years of age. It is 19 or 21 in some states. Any signature prior to that age would not be binding.
it is iilegal because u need to write it by hand or might think forgeryAdded: A "signature" is exactly what it's name implies, a handwritten personally signed representation of the signers full and...