Online slot machines use cryptographic hashing, specifically the SHA-256 algorithm, to determine game outcomes. Unlike physical slot machines that use a computer chip to cycle through numbers, online slots generate a hash from a combination of server and player inputs. This hash translates into a random number that is then used to determine the game's result, such as the position of reels in a slot game. The process ensures that neither the player nor the casino can predict or manipulate the outcome once the spin button is pressed.