These sources collectively discuss the concept of legacy system modernisation across various industries, emphasising the shift towards digital transformation. Several documents focus on methodologies and technical approaches for updating outdated systems, such as wrapping, XML integration, database replication, and complete system rebuilding, noting the importance of choosing the correct strategy based on business needs. A significant theme is the role of emerging technologies, particularly the integration of Artificial Intelligence (AI) and data and analytics, to enhance capabilities like decision-making and personalised services. Furthermore, extensive guidance from NIST is provided on securing complex systems like Operational Technology (OT) and critical public infrastructure, detailing the inherent risks and recommending robust cybersecurity frameworks, such as the defence-in-depth approach and the NIST Cybersecurity Framework, to protect these vital systems.