Food

Food is one of the five main resources in the game, next to iron, lumber, stone, and gold.

Uses
Food is consumed by the following actions:
 * Construction of buildings
 * Researching technologies
 * Dispatching troops
 * Feeding troops (done automatically)

Food is a very important resource for bigger players, as large armies need food in order to be able to be sent out. If a city runs out of food, different things might happen, depending on whether you are playing Age I or Age II:

Age I Units will start running away from your city, so it is very important to always have food available for them to eat

Age II In Age II, troops do not run away, and the city starts getting supported from your other cities, meaning that they will transport food there continuously for free, meaning that it does not send troops and it does not take up a rally slot. This will go on as long as the other cities have food. Once they run out, you are pretty much stuck, and have try some of the ways of getting food below (or dismiss some of your troops, so that your food production is positive again)

The amount of food consumed by your troops is shown when hovering over food section of the sidebar on the right. The line called Troops Upkeep is the amount of food that is subtracted from your brutto production (what your farms produce), to form your netto production, which is what you actually get per hour (the number shown to the right of the amount of food available). Food is the only resource that is consumed by troops on an hourly basis, all other ones are only required for training

Acquisition
Food is produced by Farms, but it can also be won on the Wheel of Fortune, or farming NPCs for resources. If done correctly, large amounts of food can also be acquired by trading with resource (i.e. buying a resource for a cheap price and selling it for a more expensive price), although this is not so easy, as food is always wanted and needed by bigger players, so prices will usually be relatively high.