Durak (Russian: дурак, IPA: [dʊˈrak] ^ⓘ; lit. 'fool') is a traditional Russian card game that is popular in many post-Soviet states. It is Russia's most popular card game, having displaced Preferans. It has since become known in other parts of the world. The objective of the game is to shed all one's cards when there are no more cards left in the deck. At the end of the game, the last player with cards in their hand is the durak or 'fool'.

The game is attributed to have appeared in late 18th-century Russian Empire and was popularized by Imperial Army conscripts during the 1812 Russo-French war. Initially a social pastime of uneducated peasants and industrial workers, after the October Revolution Durak has spread to numerous social levels by mid-20th century to soon become the most popular Soviet card game.

The game is typically played with two to five people, with six players if desired, using a deck of 36 cards, for example a standard 52-card deck from which the numerical cards 2 through 5 have been removed. In theory, the limit for a game with one deck of 36 cards is six players, but this extends a considerable advantage to the player who attacks first, and a considerable disadvantage to the player who defends first. Variants exist that use more than one deck.

The deck is shuffled, and each player is dealt six cards. The bottom card of the stock is turned and placed face up on the table, its suit determining the trump suit for the current deal. For example, if it is the 7 of diamonds, then diamonds rank higher than all plain-suit cards. The rest of the pack is then placed over the turn-up at right angles to it so that it remains visible. These cards form the prikup or talon. The turn-up remains part of the talon and is drawn as the last card. Cards discarded due to successful defences are placed in a discard pile next to the talon.

The player who has the lowest trump card will be the first attacker (note that there is no obligation to play that lowest trump card as the first card). The player to the attacker's left is always the defender. After each round of attack play proceeds clockwise. If the attack succeeds (see below), the defender loses their turn and the attack passes to the player on the defender's left. If the attack fails, the defender becomes the next attacker.

Cards are ranked 6 7 8 9 10 J Q K A (ascending order, ace high). A trump card of any rank beats all cards in the other three suits. For example, a 6 of trumps beats an ace of any other suit.

The attacker opens their turn by playing a card face up on the table as an attacking card. The player to the attacker's left is the defender. They respond to the attack with a defending card.

The defender attempts to beat the attack card by playing a higher-ranking defending card from their hand. For example, if the attacker plays a 7♠ the defender must play a higher spade such as the 10♠ or a card from the trump suit to defend successfully. The defender must play a higher card of the same suit as the attack card or play a card of the trump suit (there is no obligation to play the card of the same suit; you can use trump cards to beat off the attack anytime). The defending cards are placed on top of the attack card overlapping it, so both cards are visible and it is clear which cards are attacking and defending cards.