How can I find out my Facebook login name?What must I enter here:
How can I find out my Facebook login name?
facebook;credentials
If you're asking so that you can login to your account:Use the Forgotten account? link.  This allows you to get your information by using your:EmailPhone number (if set up)Username (which it sounds like you're looking for, so you would want to use one of the other options)Full NameYou can also associate multiple emails to the same account, and you can choose whether each shows on your timeline.  That way you can keep it up to date, but not have to worry about what your Friends can see.If you can already login:Once you login, you can view your username by clicking on your name at the top of Facebook (your user picture with your name next to it that takes you to your timeline).  Once you're on your Timeline, the URL has your username.If the URL says: https://www.facebook.com/hellomynameisjoeThen your username is hellomynameisjoe.