Warcraft III takes place on a map of various sizes, such as large plains and fields, with terrain features such as rivers, mountains, seas or cliffs. The map is initially hidden from the player and becomes visible only through exploration.[1] Areas no longer visible in range of an allied unit or building are covered by fog of war, meaning that while the terrain is still visible, changes such as enemy troop movement and building construction are not.[1] During the game, players must establish settlements to obtain resources, defend against other players, and train units to explore the map and attack computer-controlled enemies.[2] There are three main resources managed in Warcraft III: gold, wood, and food.[3] The first two are needed to build units and buildings, while food limits the maximum number of units a player can control at one time.[2] Additionally, producing units above certain amounts will reduce the amount of gold you can earn, forcing players to focus on playing with a limited number of units