Materials are required to make things
Food is required to feed things
Science is required to research new technologies
Troops make up your armies
Armies are made up of troops
Retreating makes your armies retreat
This merges armies, which will make them stronger but increase upkeep in food.
This splits armies, this will decrease upkeep though make them weaker.
Places a city when you have an army selected.
Selects the next idle city that isn't doing anything
Selects the next idle army that isn't doing anything