The Cyber-Physical Systems (of Systems) we design, maintain and above all, evolve, over increasingly long periods of time, are ever increasing in complexity. In the meantime, demands on quality, maintainability, sustainability, etc. become more and more stringent. "Digital twins" have been shown to enable a host of desirable extra-functional system features such as condition monitoring, fault diagnosis, and predictive maintenance. There has been a proliferation of terminology, examples and standards for digital twins. This tutorial unifies and structures these under the "twinning" umbrella, building on many existing techniques, software architectures and standards from real-time simulation and execution, co-simulation, systems and control theory, IoT, knowledge management, machine learning, surrogate modelling, etc. In the twinning paradigm, a twinning architecture (a system in its own right) is used whereby a virtual instance of a System under Study (SuS) or "asset" is continually updated with the SuS's health, performance, maintenance, etc. status information, and this throughout the asset's life-cycle comprising requirements analysis, design, production, assembly, operation and optimization, maintenance, re-purposing, and ultimately disposal. Such an asset could be physical, software, or even conceptual (such as human institutions) and combinations thereof. The tutorial takes a product family/line approach to structure desirable system features, the different workflows and conceptual twinning architectures needed to realize these, and finally, the different means to deploy/realize these architectures.

@inproceedings{VangheluweP26,
  title = {From Digital Twins to the Twinning Paradigm (What Every Software Engineer Should Know)},
  author = {Hans Vangheluwe and Randy Paredis},
  booktitle = {FSE},
  year = {2026},
  doi = {10.1145/3803437.3804906}
}