Digital twin technology is not a novel concept for the aerospace and defense (A&D) industry; however, it is emerging as an increasingly important one. Simply put, a digital twin is a virtual replica of a physical system whose performance it can help optimize. Because it exists purely in the virtual space, the twin can be stress-tested, assessed, and its design modified with no safety implications and at optimum cost, so that all the experimentation and major decisions can be nailed before the physical asset itself is touched. Given the multitude of challenges faced by A&D, including supply-chain disruption, the imperative to lower the total cost of ownership (TCO), the skilled labor shortage, an aging workforce, safety and regulatory-compliance requirements, the need to reduce carbon footprint continually for a sustainable growth, the ability to address these questions virtually before committing to a phyiscal solution makes digital twin an invaluable tool to drive the industry towards its goals.