Definition of knockout
A KO tournament or knockout tournament (it's the same thing) is a tournament in which a bounty is put on the head of all players. You will see knockout tournaments advertised as follows: 10??? + 5??? + 1???. The 10??? is the regular buy-in for the tournament. This money goes into the prize pool. The 5???? is the bounty placed on your head and the 1??? is the rake you have to pay to the cardroom (also called commission or fee). If a player eliminates you, he will get your 5???. If you eliminate players, you will get 5??? each time.
Dynamics of knockout tournaments
In a knockout tournament, the incentive to eliminate players becomes twofold. Not only do you want their chips to increase your chances of winning the tournament, but you also want their bounty. Note that the bounty is awarded to the person who wins the last chip of a player. So if you have 1999 chips and your opponent has 2000 chips, if you both go all in and win the prize pool, your opponent will have 1 chip left. The person who manages to win that chip will win the bounty. Expect this hand to be played aggressively!