These slides give an overview of TCAD history and status as in 2021. TCAD became more and more important for technology development. However, TCAD capabilities are not well known and somehow not very well understood by semiconductor industry executive management. An overview of the DTCO flows proposed by Synopsys, Silvaco and GTS are presented in these slides. Some indications are also given on how TCAD can be linked to the Design Flow (EDA), in order to start very early design before any silicon is available. TCAD today is not anymore, an isolated activity, it is a hub where technology, device and circuit design optimization can interact.