Скачать или смотреть Developers use “concurrency” and “parallelism” interchangeably — but they’re not the same thing

We often hear developers use “concurrency” and “parallelism” interchangeably — but they’re not the same thing.

This image explains it perfectly.
👉 Concurrency is about dealing with multiple tasks at once — switching between them efficiently.
👉 Parallelism is about executing multiple tasks at the same time — truly running side by side.

In Node.js, for example, the event loop gives us concurrency — it doesn’t block other operations while one task waits (like a non-blocking I/O).
But if we want parallelism, we use Worker Threads or child processes, allowing true multi-core execution.

Understanding this difference changes the way you design systems.
Concurrency improves responsiveness.
Parallelism boosts performance.

And the best systems?
They often use both — smartly.

#Nodejs #Concurrency #Parallelism #SystemDesign #JavaScript #ProgrammingConcepts #DevelopersLife