Quantum key distribution (QKD) is a secure communication method that uses the principles of quantum mechanics to share encryption keys between two parties. It ensures that any attempt to eavesdrop on the key exchange will be detected, as observing quantum states alters them. In QKD, information is typically transmitted using quantum bits or qubits, which can exist in multiple states simultaneously. This unique property allows the sender and receiver to create a shared secret key that is theoretically immune to interception, making it a promising technology for secure communications in the digital age.