juniorConcurrency
What is Concurrency vs Parallelism?
Updated Apr 28, 2026
Short answer
Concurrency is about dealing with many things at once (task switching), while Parallelism is about doing many things at once (simultaneous execution on multiple cores).
Deep explanation
At a junior level, understanding the physical and logical boundaries of execution is key. Processes are heavy and isolated; threads are light and shared. Concurrency is a logic property (how you structure code), while parallelism is a hardware property (how code actually runs).
Real-world example
A web browser: One process for the UI, separate threads for rendering, networking, and scripts.
Common mistakes
- Thinking that multi-core processors always mean parallelism without proper software support.
Follow-up questions
- How does a CPU scheduler decide which thread runs next?