Thread vs Process: What’s the Difference?

When you write software, you often want it to do multiple things at once.
This is where processes and threads come in — both allow concurrency, but in different ways.

What is a Process?

• A process is an independent program running on your system.
• Each process has:
  • Its own memory space.
  • Own resources (file descriptors, sockets).
  • At least one thread (the main thread).

Example:
If you open Chrome and VSCode, each one is a process.

What is a Thread?

• A thread is a unit of execution inside a process.
• All threads in the same process share:
  • Memory (heap, global variables).
  • Resources (open files).
• But each thread has its own stack and execution state.

Example:
Chrome can have one thread for rendering a page, another for network requests, another for JavaScript.

Key Differences

Example in Code

Python multiprocessing

from multiprocessing import Process

def work():
    print("Process is running")

if __name__ == "__main__":
    p = Process(target=work)
    p.start()
    p.join()

When to Use

Processes

• Good for CPU-heavy tasks.
• Strong isolation.
• More stable but heavier.

Threads

• Good for I/O-bound tasks (networking, disk).
• Faster communication.
• More efficient but less safe.

Summary

• Process = independent program with its own memory.
• Thread = lightweight execution unit inside a process.
• Use processes for isolation, threads for performance.