How should I answer when asked for my name by strangers online... And why?

Wow who even cares. Why would you even need to respond to messages by strangers and who cares about a name, it's not like giving out your social security number lol. Just say your first name, you don't owe everyone your full name and I doubt they demand it. If I casually asked someone I was communicating with "whats your name" i'd think I was dealing with some kind of a obnoxious neckbeard if he suddenly went on a rant about "going by many names". Like chill dude, I just asked what your first name is because that's something that tends to be public knowledge and something you'd know about someone you're talking to.