Can someone explain the exact definition of concurrency in simple terms? or What’s the real-world def

Concurrency is when your code *could* run in any order, but it’s up to the system to decide how. Parallelism is when it *does* run at the same time.

For a hands-on example, try running threaded vs. multiprocess code in Python—you’ll see the difference in the definition of concurrency vs. parallelism real quick.