The 18th volume of ToPNoC contains revised and extended contributions based on the lectures delivered during the 6th Advanced Course on Petri Nets, ACPN 2023. The 7 lectures and 4 practical papers address topics such as modelling distributed systems; Petri Net essentials; semantics of concurrent systems; a method for synthesising Petri net models from given transition systems; the Reachability Problem in Petri nets; model checking timed and strategic properties; analysis and synthesis of subclasses of Petri nets; design decisions in process discovery; extracting event logs; application of coloured Petri nets for modelling software architecture; and Petri net model checking.