Host Advantage
In online gaming, when the player who hosted the room or server has the upper hand due to him having no network lag to himself since he hosted the server.
Host advantage on COD4: In COD4, a knife only match is easy for the host to pwn in since there's no lag. Anyone else that's not perfectly connect will be lucky to even score a hit on the host.
Host Advantage
When a host has zero lag due to him hosting the games whilst others have to deal the constant lag, thus making them an easy target for the host.
No let me host the game because you're always having host advantage.