Trade
Trading happens in two ways: through external merchants or your own traders via Trade Tent.
Merchants: merchants sometimes come to your village and offer their goods. Each merchant has one of the following specializations: equipment, resources, or food. A merchant's specialization affects which goods are more cost-effective to trade with the merchant. Take items you want to sell and go to the merchant. Give him your resources and take the resources you need from him, then balance the difference with gold and trade.
Traders: once you research the trade science, you can assign a peasant to be a trader. Build a Trade Tent and manage trade orders while your trader does all the routine work for you.
Trade prices refresh once per day depending on trades completed, events, difficulty, and the development level of the world.