Quantum Key Distribution (QKD) offers a revolutionary method for secure key exchange by exploiting the principles of quantum mechanics. This paper comprehensively reviews the pioneering BB84 protocol, its experimental realization using IBM's Qiskit framework, and the underlying quantum computing concepts. We detail the methodology including qubit encoding, measurement, basis reconciliation, and key sifting, and discuss performance metrics such as the Quantum Bit Error Rate (QBER) and key generation rate. Experimental results obtained on IBM Quantum hardware are presented and analyzed, highlighting the robustness of the protocol and its security implications. The review underscores the importance of integrating QKD with future-proof encryption schemes in a quantum-enabled era.