Concurrency is a semantic property of a program or system. Concurrency is when multiple tasks are in progress for overlapping periods of time. Note, here we are not talking about the actual execution of the tasks, but the design of the system – that the tasks are order-independent. So, concurrency is a conceptual property of a program or a system, it’s more about how the program or system has been designed.
Imagine that one cook is chopping salad while occasionally stirring the soup on the stove. He has to stop chopping, check the stove top, and then start chopping again, and repeat this process until everything is done.
As you can see, we only have one processing resource here, the chef, and his concurrency is mostly related to logistics; without concurrency, the chef has to wait until the soup on the stove is ready to chop the salad.
