Well for your 3 darts you have a little timer. If that gets to 0 you obviously lose the game. But sometimes your dart doesn't come up on screen so there is no way to throw it. This means that you have disconnected. The timer will get to one second(with you unable to throw a dart, as there isn't one to throw, if you get what I mean lol) and then the screen will momentarily go black and say trying to reconnect to the server. Suddenly, you'll be back! It will be your opponents turn and your only loss is that you don't get to throw your dart so don't get any points(which is a lot smaller loss than losing the entire game!). In the comments box, it will say connection to server has been restored.
As you can tell it's hard to put into words!! :D