1:A white, adult, male, virgin usually suffering from some form of autism
2:One who pretends to be a hacker, although they're only capable of DDOS attacks on websites through sheer numbers, and occasionally defacing a myspace page.
True hackers crave recognition, after all.
3:One who hides behind anonymity so as not to be exposed for the sad, lonely, obese, gollum-like creature they truly are.
Dude: "why doesn't he ever make eye contact?
Dude 2:"he must be a /b/tard."
"without /b/ i'd never experience any social interaction, thanks 4chan!"