The showdown is the last part of the game in which the remaining players reveal their cards and compare them to determine who holds the best hand and who is the winner of the game round. The showdown takes place in this case after the last round of betting.
Showdown also refers to uncovering the player cards after one or more players have gone all-in in the round. All their money or all their chips have set and it is no longer possible for all players to make any bets, either because he went all-in himself, or because all his opponents are all-in. In this case, the players’ cards are revealed and the round is played to the end, but without further betting round. For example, Texas Hold’em shares the remaining community cards and then determines who the winner is.
Whether the players reveal their cards in the mentioned situation or not depends on the game form and the house rules.