Late surrender in blackjack refers to a rule that allows players to forfeit their hand and recover half of their bet after the dealer checks for blackjack. If the dealer has a ten-value card or an ace, players can choose to surrender if they believe their hand is unlikely to win. This option helps mitigate losses in unfavorable situations, but it is only available after the dealer has checked for a blackjack. Choosing late surrender can be a strategic decision based on the player's hand and the dealer's upcard.