When is the game saved, and how?
Solution 1:
In terms of your inventory and such, there is no such thing as the game "saving", updates are instantly applied to the server, so it isn't possible to lose anything. In terms of quests, there are frequent "checkpoints" throughout the game (usually about every 5-10 minutes). Anytime you stop playing, you will resume the quest from your last checkpoint the next time you start again. There is no way to force a quest save other than reaching one of these points.