Protection
During the first 72 hours after you have registered and the round has started, you are under protection during which time you cannot invade or be invaded, or take any kind of magic or espionage against others or they against you. You can however access the Council for your Realm.
For players who join when the round starts, protection is synonymous with the first three days of the round.
Simulating
Because of the safety of being in protection, most players make sure to plan it as best as possible to ensure they reach the desired combination of land, building composition, OP, and DP for their strategy.
To do this, players create simulations ("sims") of protection using the OpenDominion Simulator originally created and maintained by Blackreign and now maintained and updated by Yami.