Dominion cards are classified into several "types", which determine how they can be used during gameplay and how they interact with other cards. A card's types are listed on the bottom of the card.
The majority of cards have only one type, but some cards have two or even three; one card has four (Dame Josephine, who is an Action–Attack–Knight–Victory card). If a card has multiple types, it has membership in all of them for all purposes. For instance, Harem is a Treasure–Victory card; cards that have a special interaction with Treasure cards, such as Mine, and cards that have a special interaction with Victory cards, such as Scout, will both respond to Harem.
A card is not a member of types that are not listed on the bottom of the card, even if they have abilities that resemble those of cards of that type. For instance, Masquerade can be used to put undesirable cards into an opponent's deck, or to trash desirable cards from it, but it is not an Attack card because it does not have "Attack" listed at the bottom of the card.
Many card types are associated with a specific color; on cards of a given type, the background frame surrounding the card art and text are tinted in the appropriate color. Cards with rare combinations of types usually have two colors.
Cards of these four types occur in all or almost all games of Dominion, and can appear as the only type on a card.
- Action. Action cards may be played during the Action phase of a player's turn; a player may play only one Action card unless some effect provides him with "+ Actions". They may have a variety of different effects when played. The majority of Kingdom cards are Actions, but not all; so it is possible to play a game of Dominion with no Action cards. (The probability of this happening by chance is on the order of 10–10.) Action cards have white frames unless they are also Reactions, Durations, or Ruins.
- Treasure. Treasure cards may be played during the Buy phase of a player's turn; any number of Treasure cards may be played in any order. Most Treasure cards provide some number of + ; some have other effects when played in addition (or instead). All games of Dominion include the basic Treasure cards Copper, Silver, and Gold; other basic Treasures are added under certain circumstances; and some Kingdom cards are Treasures as well. Treasure cards have yellow frames.
- Victory. Victory cards are usually worth victory points at the end of the game to a player who has them in his deck. All games of Dominion include the basic Victory cards Estate, Duchy, and Province; the additional basic Victory card Colony may be included in games using Kingdom cards from Prosperity; and some Kingdom cards are Victory cards as well. Victory cards have green frames.
- Curse. Curses are worth –1 victory point at the end of the game, and are the only card type to consist of only one card name. All games of Dominion include Curses in the supply, though in many games Curses will never be gained or otherwise interacted with. They have purple frames.
Cards of these types appear in many or most of the Dominion expansions, but never appear as the only type on a card.
- Attack. The "Attack" type has no special rules of its own, but several cards refer to the type and interact with Attack cards—for instance several cards have special effects that are triggered when an Attack card is played. All Attack cards are also Actions. Attack cards usually inflict harmful effects on the opponents of the player who plays them, though not all cards that have the potential to harm opponents have the Attack type. This type does not have a color.
- Reaction. Reaction cards have optional effects that are triggered by specified events (e.g., an Attack card being played or a card being gained) when the card is somewhere not visible to players other than its owner (e.g., its owner's hand). When a Reaction card is triggered, on any turn including his own, the owner may reveal it and carry out whatever abilities it has. Reaction cards have blue frames.
Cards of these types typically occur in only one Dominion expansion.
- Duration. Duration cards have effects that often last beyond the turn they are played; they are not discarded from play until the Cleanup phase of the last turn on which they do something. All Duration cards are Actions. Duration cards appear in Seaside and Adventures, and have orange frames.
- Prize. Prize cards sit outside the supply and may be gained only as an effect of playing Tournament. Prizes appear in Cornucopia and are not associated with a color.
- Shelter. Shelter cards may replace Estates in players' starting decks in games using Kingdom cards from Dark Ages. There are three differently-named Shelters; each player starts with one of each. Shelters do not appear in the supply and may not be gained from anywhere; the only ones in the game are the ones players start with. Shelters appear in Dark Ages and have red frames.
- Looter. Looter cards have effects that can cause Ruins to be gained; in a game in which one or more Looters are present (in the Supply or via a Black Market deck), Ruins are included in the supply. All Looters are Action cards. Looters appear in Dark Ages and are not associated with a color.
- Ruins. Ruins are cards with very weak (but not harmful) effects that are included in the supply in games using Looters. There are five differently-named Ruins, but a single supply pile which is shuffled, so players do not know which Ruins are in the supply in what proportions or in what order. All Ruins are Action cards. Ruins appear in Dark Ages and have brown frames.
- Knight. Knights are a single Kingdom card pile consisting of ten differently-named cards with similar but distinct effects. The Knights pile in the supply is shuffled, so players do not know in what order the Knights will be available to be gained. All Knights are Action–Attack cards. Knights appear in Dark Ages and are not associated with a color.
- Reserve. Reserve cards can be saved for later use. They appear in Adventures, and it is not yet known if they have a color associated with them.
- Event. Events give players things to buy other than cards. They appear in Adventures, and it is not yet known if they have a color associated with them.
- Traveller. Travellers, when discarded from play, can be exchanged for stronger cards. They appear in Adventures; they aare not associated with a color, but are marked with large arrows.
In early drafts of Dominion, there was a type called "Token", which included Curse and Confusion. When Confusion was cut from the game, the type was renamed after its only remaining member, Curse.