Quantum information and communication technology will lead us to the new era of ultra-fast and absolute-secure networks. With the emergence of quantum supremacy on the horizon, the security of various classical encryption systems soon may be deemed obsolete. As a remedy, quantum key distribution (QKD) is proposed as a novel quantum-based secret keys exchange, which is developed to solve the problems of legacy encryption. It is anticipated that QKD will provide stronger security for future communication systems even in the presence of malicious quantum attacks. As the QKD research and development is getting mature, the theoretical use cases of QKD in various industries are proliferating. In this treatise, we summarise the potential applications of QKD for future communication technology while highlighting the ongoing standardisation efforts essential for the sustainability and reliability of the near-future deployment. Additionally, we also present the various challenges faced by both discrete variable and continuous variable QKD schemes hindering their widespread implementation into our future communication networks.