Leet, leetspeak and 1337 all describe the same thing. We will look at the meaning of leet, leetspeak and 1337, where the terms originated and their use in a few example sentences.
Leet, leetspeak and 1337 refer to an internet language. This language is composed of letters, numbers and symbols from ASCII to make words. ASCII is an acronym that stands for the American Standard Code for Information Interchange. Examples of leet are n00b, lolz, @$$ and c3n50red. Leet was first used on internet bulletin boards in the 1980s, The hacker group Cult of the Dead Cow is credited with coining the term. Leet was invented to confound text filters. The word leet was derived from the word elite, alluding to the elite status proficient computer users attained. This elite status entitled the users access to various files, games and chat rooms. Today many, but not all, leet words have found their way into the mainstream. The word leet may also be used as an adjective to signify that someone has masterful skills in programming or hacking.
Examples
He embraced the new nickname and tried to change is screen name to “deadmouse” but found the Internet Relay Chat channel he was using limited usernames to eight characters. Using leet spelling, he became deadmau5. (The Hollywood Reporter)
Smathers asked for a copy of all documentation available to FBI agents, personnel, and contractors, regarding the understanding of “leetspeak,” or online jargon in which users replace letters with other keyboard characters to form phonetic words. (PC Magazine)
But it is not one of those desperately “l33t”, hackerly cabals which scorn the rest of humanity for being “dialups”, which are the slow 14.4 kbps phone lines which connected to the early internet. (The Indian Express)