Own (aka pwn) is 1337-speak for dominating another player character or mob. Very few people actually use the term own; it is (essentially) invariably purposely spelled "pwn", although in speech they would probably pronounce it "pown" (or "pone") — though the correct pronunciation would be "poon" based on the fact there are no vowels in the word. Many players will use "pwn" or the past tense "pwned", "pwnd", or "pwnt" jokingly. The word is also purposefully used incorrectly as a noun, "That battle was pwnage!" or in a noun-phrase "I am The Pwnage!"
- "I pwned that goretusk!"
- "U dueld me now I pwn you!"
Younger gamers are steadfast in their belief that the origin of this word dates back to the days of WarCraft when a map designer misspelled "Own" as "Pwn". What was originally supposed to be "player has been owned" was "player has been pwned".
Older gamers, those that were around before video games and those that grew up using BBS's for online entertainment, will argue that the origin of this word dates back several hundred years ago to the game of Chess when checkmating your opponent with a Pawn, the lowest valued chess piece, was termed Pawned and, without using l337 speak, simply typed pwn, pwnd, etc. when executing this form of checkmate.
It is, however, more likely that the origin of the word is the same as that of ZOMG in that it was actually just a typo, having had the character "P" pressed instead of the character "O" — which is just to the left on the standard keyboard.
There have also been rumors of foreign keyboard construction types lacking certain keys, most notably the "O" and "L" keys, hence other misspellings supposedly performed on purpose by players with said keyboards. Some examples would be: "KIK" instead of "LOL" or "KK" rather than "OK"; but this is only speculation.
The end result is the same; one would rather pwn than be pwnd themselves. The term grew from there and is now used throughout the online world and especially within online games.