Insurance in Blackjack is a side bet offered when the dealer shows an Ace, allowing players to wager up to half their original bet that the dealer has a Blackjack. If the dealer has a Blackjack, the insurance bet pays 2:1; if not, the player loses the insurance bet. It is strategically advisable to take insurance only if you have a strong hand, like a total of 20, and have reason to believe the dealer is likely to have a Blackjack.