Side bets in blackjack are additional wagers that players can make alongside their main bet, typically based on specific outcomes or events within the game. Common side bets include options like "Perfect Pairs," which pays out if the player's first two cards are a pair, or "21+3," which combines the player's two cards with the dealer's upcard to form a poker hand. Side bets often have higher payouts than standard blackjack wins but generally come with a higher house edge, making them riskier.