Quantum Key Distribution (QKD) is one of the most groundbreaking advancements in the field of cryptography, offering a level of security that classical cryptographic methods cannot match, particularly in the face of emerging quantum technologies. Unlike traditional key exchange mechanisms that rely on the computational difficulty of mathematical problems (e.g., RSA, Diffie-Hellman), QKD leverages the intrinsic principles of quantum mechanics, fundamentally reshaping the way we think about secure communication. At its core, QKD provides an unbreakable method of sharing encryption keys between two parties, typically referred to as Alice (the sender) and Bob (the receiver). The revolutionary aspect of QKD is its use of quantum particles—often photons—to transmit key information. Due to the unique nature of quantum particles, any attempt by a third party (commonly referred to as Eve, the eavesdropper) to intercept or measure these particles alters their state. This property ensures that Alice and Bob can detect the presence of an eavesdropper with absolute certainty, guaranteeing that the communication channel is secure.