Stone

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

Uses
Iron is consumed by the following actions:
 * Construction of buildings
 * Construction of fortified units
 * Researching technologies

Stone is only important in the early game, but after the first cities are fully upgraded, it is not very important for much and the price will therefore be extremely low, as everyone is trying to get some gold out of it, while beginners are very happy with cheap stone. However, do not build a stone city on most older servers, as you will not be able to sell large amounts of it for gold anyway.

Acquisition
Stone is produced by quarries, but it can also be won on the Wheel of Fortune, or farming NPCs for resources.