Each card is worth a certain number of points. All numbered cards are worth their printed value, while face cards are worth 10 points each. Aces can be worth 11 points or one, depending on which is more beneficial for the hand.
For players, the object of the game is to beat the dealer by having a more valuable hand, one that is as close to 21 as possible without going over. The best possible starting hand is, appropriately, called a blackjack – and it is made up of an ace and any ten-point card. This “natural 21” will pay out at 3-2 odds, unless the dealer has also made one; in that case, the two hands push.
At the start of the hand, should the dealer have either an ace or a ten-point card showing, they will secretly check to see if they have a blackjack. In the case of them having an ace (where it is more likely that they will complete their hand), they will first ask if the players wish to buy insurance. This bet costs half as much as your initial bet, and pays out at 2-1 if the dealer reveals a ten-point card. If that happens, the player will lose their hand bet but win the insurance, which causes them to break even for the hand. When this offer is made to players with a blackjack, it is referred to as an “even money” offer; this is because mathematically, taking the insurance bet means that the player will make the same amount of money whether the dealer shows a blackjack or not, and as such can immediately be paid even money on their initial bet.