There are three resources: food, wood and fur. They are each represented by wooden markers.
There are two kinds of food markers: perishable (ordinary) food, and non-perishable (special) food. The two types of food are are identical in game terms, except that non-perishable food is not discarded at the end of the round.
A few cards grant you non-perishable food. Otherwise, when a rule or game effect instructs you to take "food", it always means perishable food.
If a source is covered by a black marker, it is exhausted. Exhausted sources produce no resources during either the Production Phase or the Action Phase, even if there is a matching additional food or additional wood token.