Insurance is a side bet in blackjack that pays 2:1. It is offered when the dealer gets an ace, which puts them pretty close to a blackjack. The side bet is placed before the player’s decision. If you take the insurance, you will lose if the dealer doesn’t get blackjack on the next draw.
You’ll lose everything but the insurance bet (at odds of 2:1) if the dealer has a blackjack. This means that even though you’ve lost your original stake, you’ve at least won the insurance bet as a consolidation prize.
Blackjack experts never recommend taking up the dealer’s insurance offer, as it only serves as a way to take more of your money.