An insurance bet, often just called insurance, is a blackjack side bet offered when the dealer’s up card is an ace. Before the dealer checks the hole card for blackjack, each player can stake up to half of their original bet that the dealer has a natural. It appears in classic blackjack and many online and live variants, but not in every game.
If the dealer has blackjack, insurance pays 2 to 1. If not, the insurance stake is lost and the hand carries on. The side bet is settled separately from the main hand, so the outcomes can split. You can lose the insurance and still win the hand, win the insurance while the main bet loses, or win the insurance and push on the main bet. A player holding blackjack may be offered even money, which works out the same as insuring a natural.