Selling a resource will drive its price down for all players.Buying a resource will drive its price up for all players.However, other players will be affected by commodity trades done at the market: They are bought from and sold to an off-map trader rather than being sent to or taken from another player (if you want to trade resources with another player, you have to do this via the diplomacy screen). Once a nation has developed Commerce 2 (Coinage) at the Library, it may buy or sell common resources at the Market: Food, Timber, Metal, and, from Industrial Age on, Oil. When a Market is completed or destroyed/razed, a one-time bonus of 30 Wealth is granted. Researching Taxation technologies at a Temple has no effect on Market income. The only way to increase this is by building the Porcelain Tower wonder, which triples each Market's production to 30 Wealth per 30 seconds. Each Market generates a basic income of 10 Wealth per 30 seconds.
