What is '1337' or 'leet'

You might seen the word ‘1337′ numerous time in some online game forum and notice that people posting their IMBA (imbalance) equipment with unusually good options or status there. Well here’s something you should know about it if you want people recognized you as a gamer. Seems interesting enough when you get to know the word.
Definition: 1337, and its other spelling, leet, is a hacker term from the days of Windows 95. It is used to say “elite”, or just “leet” for short.
Leet comes from the mid 1990’s when an infamous hacker group would use the digital port numbered 31337 to take remote control of Windows 95 computers. The port 31337 came to be known as the “elite” port, with the jargon spelling using numbers.
To this day, 1337 and leet are used to describe very serious Internet gamers with a high level of skill. It is considered a negative connotation, and is still associated with hacking.
Related terms to leet: hax0r, chixor, 3ber, epeen, r0×0r. These hacker-type terms were originally purposely spelled with numbers to avoid censorship programs. Today, the numeric spelling is used as a form of subculture and expressiveness.
Source: http://netforbeginners.about.com/od/l/g/leet.htm