This came up as an argument. As far as I know most MMOs employ a soft "turn-based" mechanism to compensate for lag, and allow complicated actions to be performed ("cooldown" etc). They are sometimes called "tick based" systems as well.
Obviously EVE Online doesn't have a turn-based gameplay but does it employ turn-based game mechanics?
Otherise it means that faster internet connection or living in Iceland could be an advantage in combat.
Best Answer
Everything in EVE is based on a tick based mechanic. The implementation is very transparent unlike in some other massively multiplayer games but it is evident in many of the actions available in game. At the time of writing the tick speed is 1Hz. Most actions in EVE require a certain number of ticks to complete (collectively called cycles), the number of which are then modified by skills and items.
This is visible in every action - every time you target somebody, activate a module, etc - even changing direction in flight in that if you try to send too many movement based commands in quick succession they will begin to queue up (the queue is very short, so too many commands or overriding commands will result in actions being dropped from the queue) before being executed in the next tick.
For example; firing your weapons will activate a cycle. This cycle cannot be "cancelled" as cancelling it will still require the cycle to complete before you can start another. If the cycle completes in the middle of a tick, you will have to wait until the next tick before reactivating it and starting another cycle.
Additionally, the game employs a "time dilation" system in highly populated/active systems which applies a modifier to the length of all of the ticks to maintain an average load on the servers responsible for running the calculations for the actions in that system.