Why are so many user's names on here just numbers?

I can only see how many is following me. I know you can go to your profile and see all the users that are following you, and ...

Can you change your username on here??

ok..im just curious...was wonderin how many users would be online right now?? hmm...ok..just say "me" or sumthin...with your ...

can you change your user name?^^^ I know its kind of a dumb question but I cant seem to find out where it would be if you can...

I was just wondering how many users there are on this site? Thanks

So can I have multiple log ins on this site wth this name or do I have to use a different screen name?? Or Different computer??

How did you come up with your user name here on FunAdvice?

I've seen in the past week, many questions have changed to the original poster being called "fau" -- is it some type of bug? ...

Who is the user named "FunAdvice" and why do you have sooo many questions?! And how did you answer so many peoples questions?!

How many questions are on FunAdvice