Ibrahim Tanyalcin 1337 is the 1337 representation of the word "leet", which is the stylized form of "elite", which is a kind of chat-slang or encoding used by a certain internet folk. It is based on common miss-typings, easier-to-type representations, ASCII art, and just stuff which sounds cool or can be used to work around word-filters.
The "encoding" usually substitutes numbers for letters (based on how a letter and number look, for example O => 0), letters for letters (based on pronounciation, for example elite => (e)leet , hacker => haxor, U => |_|) or changes the word-order (for example porn => pron). In addition, certain characters may be capitalized in random place. Apart from the writing the slang makes use of certain rules, like the nomification of adjectives and abbreviations. You can read about that stuff in the wiki article, though the original slang is not really based on official rules, but just a living thing and people can do whatever they want as long as it is still legible and understandable by the right people. I once even wrote a small function which would 1337-ify a text as a kind of easter-egg^^ Let me give you some examples:
| Alphabet | 1337 |
| --- | --- |
| A | 4 |
| E | 3 |
| T | 7 |
| -ker | x0r |
| -and- | & or 7 |
| humilated | pwnd or own'd |
So, a 1337 string could look something like this:
71h5 73X7 15 wR1773n 1N 1337. c4n Y0U r34d i7? 1 7H1nK, 1337 15 m057Ly u53d 8Y g4m3RF4g5 4nD h4X0R5 :D
Hint: Lean back a bit and it should be pretty easy to read.
Since UTF-8 started gaining ground, I can also see more and more symbols from other alphabets used as substitution material (for example T => イ, Z => こ), and of course things like Z̗̭̗͔͕̮ͫ͌̂͝a̞̺̟͋̔͛ͧ̚͢ĺ̦͎͠g̽̄̎̎̚͝o̤̺̤̥̭̼͔͑͗̑ͩ͛ͥ , which add noise.
I don't really know how spread 1337 still is, since I guess that most people who used it grew up (look at me :D) and stopped using it; or alternatively I don't see it that often anymore, because I stopped playing with 12-y/o kids a few years ago. There is still a certain slang-aspect, especially in the gamer-world, though, which probably is here to stay!
Well, one thing I still celebrate with my (gamer) friends every day is happy-new-1337 at 13:37 PM (if you ever need a reason to party for a minute in the early afternoon...)