A language in which numbers and symbols are put together to look like letters. Some people create their own 1337 letters and it makes them look more 1337 by fellow 1337-speakers. Here is an alphabet of 1337 letters I know and have created:

A: 4 or l\ or ^ or @ or /\ or /-\
B. l3 or 8 or ß or 3 or l:
C: ( or < or © or ¢
D: l) or l> or )
E:3 or £
F: l= or # or ƒ
G:6 or 9
H: # or l-l or (-) or !-! or }-{ or }{ or l+l or )+( or !+! or }+{
L: 1 or ! or
J: _l or _/
K: l< or l( or l{ or l<=
L: l_ or ! or 1
M: l\/l or /\/\ or l\l\ or ^^
N: l/l or /\/
O: 0 or () or <> or * or ø or Ó or °
P: l* or l> or |D or l^ or l+
Q:& or (\) or ¶
R: l2 or ®
S: 5 or $ or §
T:+ or 7
U: l_l or /_/
V: \/
W:|/\| or \/\/ or |/\/ or \/\|
X: >< or }{ or :-:
Y: ¥
Z: 2

1337. Originally used by hackers to avoid simple net searches that would turn up, for example, "I am an elite hacker".

Instead hackers would say "1 4|\/| 4|\| 31337 |-|4x0|2".

"31337" was later shortened to "1337".

Now 1337 used mainly by the gaming community (also in chatrooms) to mean an especially skilled player.

n. 1. Nestled between 1336 and 1338, 1337 is commonly known as a number, or for the more advanced; an "integer"
2. Often misused to satisfy a lamen's ego, the self-proclaimed 1337 will misuse the title, pretending to hold Xtr3m H4x0r capabilties while in fact masturbating to preteen beastiality at 2:00 AM with baggy eyes; anonymously hassling n00b's with better things to do than kill their babies over mindrot such as Everquest and Warcraft. See also "colon debris" and "queefstain"

1337 is the language of hackers and newbies across the internet. Also, the words in 1337 are usually short(ie "are" becomes "r") and intentionally spelt wrong(ie "the" becomes "teh", this is most common with e switching places and o's becoming p's)

the mostly complete translation chart(exluding unicode characters, ie ©):
A=4 /-\ @ ^ /\
B=8 3 8 |3 |8
C=( {
D=) } |) |} |> >
E=3
F*=# |=
G=6 9 (_>
H=# |-| (-) )-( }{ {-} /-/ \-\
I=1 ! |
J**=_| j
K=|< |{
L=1 |_
M=/\/\ |\/| \/
N=/\/ |\| \
O=0 ()
P=|D |* |>
Q=0,
R=|2 |? |-
S=5
T=7 + ''
U=(_) |_| \_\ /_/
V=\/
W=\/\/ |/\| /\
X**=>< }{ X
Y='/ %
Z**=2 z

Common mispellings:
the = teh
that = taht
take = taek
own = pwn
you = joo
dude = jood

common phonetic replacements(always used in true 1337):
f = ph
ck == xx

*there is no 'F' in true 1337, it is replaced by the 'ph' phonetic in true 1337

**acceptable when not replaced by a symbol

Once used by the hacker community as sort of a sub-culture language, ANYONE using this type of speak in the present day in age is either:

A) A clueless net newbie who somehow thinks its still "cool" to speak this way.

B) A veteren net user who uses it to parody the type of people mentioned in example A.

1337 was the year the hundred years war started making an obscure factoid a totally useless piece of gamer common knowledge.

Leet//1337: (most commonly 1337 but often also leetspeak, leetspeek, l33t5p34k, or l33t) from the phonetic form of the word "elite", is a cipher, or novel form of English spelling. It is characterized by the use of non-alphabetic characters to stand for letters bearing a superficial resemblance, and by a number of spelling changes such as the substitution of "z" for final "s" and "x" for "(c)ks". Leetspeak is traditionally used on the Internet and other online communities, such as bulletin board systems. Leetspeak is commonly used by hackers, crackers, script kiddies, and gamers.
----However, leetspeak is not popular amongst all hackers. Many consider it a pointless affectation, and as it has become widely used it is less useful as a way of showing membership of an "elite" group. It is nonetheless a cultural phenomenon well-known amongst hackers and many other Internet users.
----Certain factions maintain that "true" leetspeak is spelled correctly, with the exceptions described above. They do not consider the use of extreme short forms (such as "b" for "be", or "u" for "you") as leetspeak; instead, they refer to it by such terms as "AOL speak". This is because they associate such habits with users who use ISPs like AOL, which is associated with "newness" and therefore not considered "elite". Another convention sometimes associated with leetspeak or Internet chatting is capitalizing every other letter (LiKe ThIs), sometimes called studlycaps or stickycaps. A similar habit involves capitalizing every letter except for vowels (LiKe THiS).

one thousand three hundred and thirty seven

(i do know the true meaning)

The number of licks it takes to get to the center of a Tootsie Roll Pop.