Is your name Constantine and you're leading some soldiers across the Tiber River in order to gain control of Rome and there is a message in the sky written in Latin? Or some voice tells you to paint crosses on your legions shields? That is a sign from God. Are you driving and see a green metal sign on the freeway with white lettering? That is a sign from the Dept of Transportation (CalTrans if you live in California)
It was created to help people with disabilities to communicate. Now people are teaching it to babies to help them to communicate in simple terms b4 they can verbalize. It is considered a form of communication.