Anonymous user
 

"Anonymous User"
This screen name indicates a guest to the forum?
Does it also indicate a post made by someone whose account is no longer active?

It is my understanding that anyone can post using that account so that they do not post under their real user account name.

I originally thought that I noticed inconsisted facts from one specific user, but it turns out that many people different people can use this one account.

I am not sure if an inactive person can post using that account.

Guests can't post. Nepenthes has it correct in that already registered users can choose to post anonymously in certain sections of the site. Sometimes when someone has been around for awhile, they'd rather not have their username linked to certain potentially embarrassing posts. It's important to note that site administrators are able to check who posted anonymously should the function be abused.

People who have been kicked off of the forum will often have "Loser" displayed under their username (where you presently have "Upright"). And, before you ask, that user title will automatically change a few times as you post more, until the magical day when you can enter a custom title. I don't remember the post thresholds anymore.

I'm pretty sure the ghreshold for a custom title is 500, and to expand on what redlemon said, "Banned" means you're banned, "Loser" is for those who fucked up badly enough that we want everyone to know they suck.