The "shifting" strategy in Blackjack involves adjusting your bet size based on the composition of the deck. When the deck is favorable (rich in high cards), players increase their bets to take advantage of the higher likelihood of getting strong hands or Blackjacks. Conversely, when the deck is unfavorable (rich in low cards), players reduce their bets to minimize losses. This strategy is typically used by card counters who can track the deck's composition and make adjustments accordingly.