Concurrency implies multiple partial computations in progress, but not necessarily that they run at the same time -- some models (e.g. a single-threaded event l

Concurrency implies multiple partial computations in progress, but not necessarily that they run at the same time -- some models (e.g. a single-threaded event loop, like Node's) explicitly guarantee mutual exclusion and define certain preemption points. Cooperative multitasking, single-threaded event loops, and futures/promises (when not pushed to a thread pool) are good examples. (I've also seen definitions of concurrency that do not imply the above, but I think the above definition is more in line with the distinction people try to make...)