True—your name is whatever you get people to call you, legally, at least in some states—but the very important caveat is that if you change your name or use an

True—your name is whatever you get people to call you, legally, at least in some states—but the very important caveat is that if you change your name or use an alias for purposes of fraud, either to defraud someone else or to defraud the gov't, that's still illegal. So for instance, it's perfectly legal for me to write my name as "Don" even though my SS card says "Donald", but then, I'm writing my actual SS# on my taxes (and paying them!), so there's no fraud.