I don't know where to post this, but what is the significance of these words that appear after usernames? They must have some kind of hierarchy, from beginner to advanced? What is their order? Or numbers of posts? When do posters get to create their own?

http://www.scienceforums.net/forum/showthread.php?t=127

I don't know where to post this, but what is the significance of these words that appear after usernames?

Apart from the special titles it is an insignificant gimmick.

They must have some kind of hierarchy, from beginner to advanced? What is their order?

They are roughly ordered from small to big.

Or numbers of posts?

Apart from the special titles for experts, moderators and administrators, it depends on the number of posts.

When do posters get to create their own?

As soon as they reach moderator or administrator status, I think. Experts have a switch to chose between "resident expert" and "<field> expert" (e.g. "Physics Expert"), afaik.

There are also other reasons for people to have custom titles such as a username change or just being really awesome.