Digital engineering is a methodological approach integrating digital technologies and models across the entire lifecycle of engineered systems. It investigates the systematic application of digital representations, simulations, and data analytics to enhance the design, analysis, manufacturing, testing, sustainment, and modification of complex products and systems. Key characteristics include the central role of authoritative source of truth models, widespread use of digital twins, model-based systems engineering principles, and collaborative digital environments. Its significance lies in enabling improved efficiency, reduced development time and cost, enhanced system performance prediction, and facilitating continuous lifecycle optimization through data-driven insights.