What is the difference between a process and a thread?

A process is an independent, isolated unit of program execution with its own address space and resources (file descriptors, memory). Creating and switching between processes is more costly.

A thread (or thread) is a lighter unit of execution within a single process. Threads share the same address space and process resources. Creating and switching between threads is cheaper.

Characteristic	Process	Thread
Address space	Independent	Shared
Isolation	Strong	Weak (within a process)
Creation/Destruction	Costly	Cheap
Context switching	Costly	Cheap
Data exchange	Via IPC (Inter-Process Communication)	Easy (shared memory), requires synchronization
Fault tolerance	Failure of one does not affect others	Failure of one can affect the entire process
Scheduling	By the operating system	By the operating system (or thread scheduler)

Example of creating a process in Python:

import multiprocessing

def worker():
    # Code executed in a separate process
    print("Worker process")

if __name__ == "__main__":
    p = multiprocessing.Process(target=worker)
    p.start()
    p.join() # Wait for process to finish

Example of creating a thread in Python:

import threading

def worker():
    # Code executed in a separate thread
    print("Worker thread")

if __name__ == "__main__":
    t = threading.Thread(target=worker)
    t.start()
    t.join() # Wait for thread to finish