Coins

Coins are Terraria's unit of currency. They are usually used for NPC transactions, but some players also accept them as payment in multiplayer.

Types of Coins
There are four types of Coins in Terraria: Copper, Silver, Gold and Platinum Coins. Each is worth 100 of the Coin of the previous rank. One Platinum Coin is worth a million Copper Coins.

Obtaining Coins
Coins can only be acquired from Enemy drops, or through trade with NPCs (or other players). Even though the Coins are "Copper", "Silver" or "Gold", it is impossible to craft them from Ore, Bars, or any other item in general (apart from a different rank of Coins).

Coin Harvest Technique
An easy way to acquire Coins is to harvest Sand Blocks, convert the sand into Glass then Bottles, before selling the result to an NPC for about 20 Silver per 99. This works because sand is especially easy to harvest. This technique makes Deserts a virtual Coin mine.

Storage
Coins can be stored in a Chest or Piggy Bank, like other items. It is recommended to always store them, as it will prevent them from being dropped upon Death, as the penalty is dropping half your carried coins (rounded up).

Inside the inventory, Coins have their own special set of 4 slots to the right of the inventory.