Cryptographic hashing in online casinos involves creating a unique hash value using the SHA-256 algorithm from a combination of inputs provided by the casino and the player. This hash acts as a one-way lock, making it impossible to deduce the original inputs from the hash itself. It's important because it ensures the game's fairness and unpredictability, as the outcome cannot be known until the player decides to spin. This technology is crucial for maintaining trust between the player and the casino.