Coin (represented by the symbol cost in Coins, even if that cost is (if a card shows no Coin cost, due to costing only or , it is assumed to have a Coin cost of ). This cost is mainly used to determine how much Coin must be fielded by Treasures and Actions to Buy a card during your Buy phase. In addition, many cards have other effects that depend on their own cost and/or the cost of other cards. A card's cost in is considered to be orthogonal to its cost in or , if it has such costs; there are no exchange rates between , , or . There are also several cards that can reduce the costs of cards in , though this cost can never go below .) is the main currency in Dominion. All cards have a
 Official Rules
- "+ " – the player has X number of additional coins to spend in the Buy phase. The player does not take additional Treasure cards for these coins.
- In the Buy phase, the player can gain one card from the Supply by paying its cost. Any card that is in the Supply may be purchased (Treasure, Victory, Kingdom, and even Curse cards). The player may not purchase cards from the Trash pile. Normally, a player may buy only one card, but he may buy more if he played certain cards earlier in his Action phase.
- The cost of a card is in its lower left corner. The player may play some or all of the Treasure cards from his hand to his play area and add to their value the coins provided by Action cards played this turn. The player may then gain any card in the Supply of equal or lesser value. He takes the purchased card from its Supply pile and places it face-up on his Discard pile. He may not use the ability of the card when it is gained.
 Sources of Coin
Almost all Treasures produce Potion produces instead; Horn of Plenty, and optionally Charm and Scepter, have gaining effects). Many Actions also produce ; subcategories of these include terminal silvers, Peddler variants, and disappearing money. Borrow can produce at the price of card draw later. The only other source of are Coffers, which are produced by certain cards from Guilds and Renaissance, and can be stockpiled for when they are most useful.(
 Uses of Coin
The most important use of Guilds may be overpaid for, allowing for to be spent on other effects (although two of the overpay effects involve gaining cards). Adventures and Empires include Events, and Renaissance includes Projects; these are special effects that can be bought during the Buy phase that are not cards. Adventures also includes Storyteller, which allows you to spend to draw cards.is buying cards. However, certain cards from
The coin symbol, Base set. All subsequent sets use a lightened version of the symbol., is markedly darker in the first releases of the
 Secret History