A Farm is a building that provides food for the colony, and requires the Farm research in the Wood Workshop.
It can be upgraded to an Advanced Farm after the corresponding research.
"Produces food by harvesting grass field from the surroundings."
The Farm takes up a 2x2 area. For every grass tile in a 2-tile area around it, the farm will place a plot of wheat; other buildings may be placed on tiles with wheat not directly next to the farm, at the cost of losing those tiles for food production. Each block of wheat provides 2 food for the colony. The plots can not be shared with other farms, as they must be built with a minimum of 4 tiles in between each other.
Even though the Farm only gives 64 food with perfect placing conditions, the maximum amount of food you can get out of a single Farm is in fact 77, through placing a Warehouse close to it, boosting the production by 20%. This value then can be doubled by upgrading the Farm to its advanced version.
Note that when being infected, a farm will generate 12 infected, which is a serious threat in early game.