A Social Digital Twin (SDT) is a sophisticated virtual model that mirrors both the physical infrastructure and the social dynamics of a city or organization. SDTs integrate data from various sources, such as IoT devices, social media, and public records, to create digital agents that represent real people and their interactions. This enables simulation and analysis of how changes in technology, policy, or environment might impact social behavior and infrastructure. In cybersecurity, SDTs help predict vulnerabilities, assess the impact of cyberattacks, and improve response strategies by modeling human factors alongside technical systems.