Quantum cryptography is an emerging technology in which two parties can secure communication by applying the phenomenon of quantum physics. The security of these transmissions is based on the principle of inviolability of laws of quantum mechanics. The quantum method relies on two important principles namely the Heisenberg Uncertainty Principle and photon polarization. The Heisenberg Uncertainty Principle states that, it is not possible to measure the quantum state of any system without distributing that system. The principle of photon polarization states that, intervening eavesdropper cannot copy unknown qubits. This paper concentrates on the theory of quantum cryptography, implementation using the quantum key distribution protocols and how this technology can be made more secure.