A basic occurrence of user participation, taking the form of a rough message that indicates this stamps machine is broken. User-generated content if I may use this term.

This sort of activity has been taken as potentially transferable to digital interfaces. Think, for instance, about GPS devices that allow people to send over some updates concerning traffic jams and constructions (and sometimes send fake information about non-existing constructions only to prevent other persons to use certain routes). A topic I address yesterday on the french radio "France Culture" (podcast here, french only, sorry about that).