Resources are the 4 different stats that are required for things like building, maintaining troops, and much more. They are Food, Iron, Stone, and Lumber. These four are gained and used even when offline, and they are represented by 4 numbers at the top of the screen. The production of each resource can be upgraded by constructing and upgrading Farms, Quarries, Iron Mines, and Sawmills
Food Food is important for feeding troops.
Iron Iron is important for production and researching.
Stone Stone is important fir production, and recruiting.
Lumber Lumber is important for production, researching, and recruiting.