Tents are cheap buildings which provide food. Food allows you to increase your population, which means the total number of your workers. Small tents provides 25 food each, so a total of 10 small tents is needed to reach max population (250), or you could upgrade them to big tents, which provides 65 food each, meaning you need 4 of them. Small tents are preffered over big tents, because big tents give 4 gold feed each when destroyed, so 4 big tents = 16 gold, 10 small ones = 10 gold. Tents should be gotten at the start of the game, and must always keep that 250/250, very cheap to rebuild.
Red color text.