Sort of, but this explanation loses too much information. Concurrency is a binary relation on tasks, which looks like Task -> Task -> Bool; if true, the order i

Sort of, but this explanation loses too much information. Concurrency is a binary relation on tasks, which looks like Task -> Task -> Bool; if true, the order in which the tasks may execute relative to one another does not matter. If false, the tasks must execute in a defined order. Astute readers will note the above function is isomorphic to the function defining whether there is an edge between two nodes in a graph (although the Bool value is flipped); indeed, task dependency graphs are a useful way of modelling concurrent systems. Concurrency has absolutely nothing to say about parallelism. If you have a computer system which is able to execute tasks in parallel, it can take advantage of information from the concurrency relation to execute two concurrent tasks in parallel. For the best implementation of this idea I've seen, I recommend taking a look at Intel's Threading Building Blocks template library.