Traders naturally spawn at random locations on the surface of survival worlds and can be found in trader's carts which are made out of wooden planks, logs, and often decorated with a variety of other decorative blocks that are only common on these carts. Trader's deal in a variety of different goods which can be bought and sold with the currency of rusty gears.
Types of Traders
As of the update of 1.10.0 there are currently nine varieties of traders: Building Materials, Commodities, Foods, Furniture, Luxuries, Treasure Hunting, Clothing, and Artisan. From trading with these individuals you are able to obtain items and blocks you can get no where else in survival.