Book excerpt: The 16th volume of ToPNoC contains revised and extended versions of a selection of the best workshop and tutorial papers presented at the 41st International Conference on Application and Theory of Petri Nets and Concurrency, Petri Nets 2020, and the 20th International Conference on Application of Concurrency to System Design, ACSD 2020. The papers cover a diverse range of topics including model checking and system verification, refinement and synthesis; foundational work on specific classes of Petri nets; and innovative applications of Petri nets and other models of concurrency. Application areas covered in this volume are: process mining, verification, formal semantics, distributed simulations, business processes, distributed systems, and net synthesis. Thus, this volume gives a good overview of ongoing research on concurrent systems and Petri nets.