Duration is a card type that was introduced in Seaside and revisited in later sets, starting with Adventures. Duration cards are cards which usually have an effect on the turn after they are played. A Duration is not discarded from play until the Cleanup phase of the last turn on which it does something - usually the turn after the turn on which it is played.
 List of Duration cards
- Guardian, Haven, Lighthouse
- Amulet, Caravan Guard, Dungeon, Enchantress, Fishing Village, Gear, Ghost Town, Secret Cave
- Archive, Bridge Troll, Cobbler, Crypt, Den of Sin, Haunted Woods, Merchant Ship, Outpost, Swamp Hag, Tactician, Wharf
- Hireling, Raider
 Official Rules
- Seaside introduces Duration cards. These cards are orange, and say "Duration" on the bottom line, i.e. "Action – Duration." A Duration card does something after your turn. Leave the card in front of you until the Clean-up Phase of the last turn in which it does something (discard it before drawing for the following turn). So if the card says "Now and on your next turn," discard it during the Clean-up phase of your next turn.
- If you play or modify a Duration card with another card, that other card also stays in your play area until it is no longer doing anything. For example if you play Throne Room on Merchant Ship, both cards stay in play until the Clean-up phase of your next turn. The Throne Room stays in play to remind you that you are getting the effect of Merchant Ship twice on that next turn.
- In order to keep track of which Duration cards are discarded during the current Clean-up phase and which Duration cards remain in play, place Duration cards in a separate row above the other Actions and Treasures played. When a Duration card has its last effect, move it to the row of cards that will be played and discarded during the current turn.
- Post-Seaside rules: Duration cards are orange, and have abilities that affect future turns. Duration cards are not discarded in Clean-up if they have something left to do; they stay in play until the Clean-up of the last turn that they do something. Additionally, if a Duration card is played multiple times by a card such as Throne Room, that card also stays in play until the Duration card is discarded, to track the fact that the Duration card was played multiple times. Keep track of whether or not a Duration card was played on the current turn, such as by putting your cards into two lines (older cards and this turn's cards).
 Other rules clarifications
A Haven, Tactician, Gear or Archive played without meeting the criteria for its next-turn effect (setting aside or discarding) will be discarded from play the turn it was played. An Outpost that fails to create an extra turn remains in play until the next Clean-up phase, whether your own, or that of the next player, since it checks whether or not it can create an extra turn after it's too late to clean it up. Champion and Hireling remain in play permanently. Archive may stay in play for two turns after the one it was played (if it set aside 3 cards). In all other cases, the Duration will stay in play until the Clean-up phase of your next turn.
When you use a Throne Room variant on a Duration, it stays in play, even if multiplying the Duration's effect is not meaningful, such as Throning a Tactician, or Throning an Archive with 3 or fewer cards remaining in your deck. Procession never stays in play, as any Duration it doubles gets trashed that turn anyway.
Effects that resolve at the start of your turn can be resolved in any order; this includes multiple plays of the same Duration card by a Throne Room variant. For example, if you played a Wharf and then a Throne Room on an Amulet last turn, on this turn you could choose to first gain a Silver from the first Amulet play, then draw 2 cards from Wharf (perhaps triggering a reshuffle and maybe drawing that Silver), and then choose to trash a card from the second Amulet play, now that you have more cards to choose from.
Although the Seaside rules do not mention this explicitly, a Duration card still in play when the game ends is returned to its owner's deck before scoring; this can matter for alt-VP cards such as Gardens.
There are a couple of cards from outside Seaside and Adventures that have effects on subsequent turns: Possession and Prince. Despite their functional similarity, these are not Duration cards and the Duration rules do not apply to them: for example, unlike Outpost, Possession is discarded before the extra turn it creates; and Prince is set aside to perform its future-turn functions, rather than remaining in the play area as Duration cards do.
On the turn on which they are played, Duration cards typically have weak effects (relative to their cost), or even detrimental effects; their strength comes in part from the fact that their effects on the next turn do not consume an Action to play or a card slot in your hand. For example, Caravan, on the turn it is played, is a cantrip with no effect; on the next turn, however, it gives you a sixth card in your hand for free—thus playing a Caravan on one turn has the same effect as playing a Laboratory on the next turn.
Although Duration cards' next-turn effects are typically quite strong, they cost less than and are usually considered weaker than cards that have those same effects immediately—for instance, Caravan costswhile Laboratory costs . This is in part because it's better to receive benefits earlier—playing a Caravan on the last turn of the game gives no benefit while Laboratory does—and in part because the fact that Durations stay in play for two turns is a disadvantage, since it means that they can actually be played less frequently. For instance, it's possible to draw an extra card every turn by having a single Laboratory and playing it every turn; in order to play a Caravan every turn, you have to have two copies of the card.
Reserve cards can play rather similarly to Durations; most have a weak effect now for a stronger effect later. The difference is that Reserves don't have to be triggered on your next turn; you can wait a few turns to use them, or even use some of them the same turn you play them.
 In other languages
- Czech: Dlouhodobá
- Dutch: Duurzaam (lit. sustainable)
- Finnish: Toistuva (lit. recurring)
- French: Durée
- German: Dauer
- Polish: Następstwo (lit. succession)
- Russian: Длительность (pron. dlityelnost)