In blackjack, hitting and standing are two fundamental choices a player makes during their turn. Hitting involves requesting an additional card from the dealer to improve the player's hand total, which can increase the risk of exceeding 21 and busting. Standing, on the other hand, means the player is satisfied with their current hand value and chooses not to take any more cards, effectively ending their turn. The decision between hitting and standing depends on the player's hand total and their strategy against the dealer’s visible card.