Explain the concept of multithreading and multiprocessing in Python. When would you choose one over the other?

Multithreading and multiprocessing are techniques for achieving concurrency in Python. Multithreading involves running multiple threads within the same process, sharing the same memory space, while multiprocessing involves running multiple processes, each with its own memory space.

You would choose multithreading when your tasks are I/O-bound and can benefit from concurrent execution, as threads share memory and are lightweight to create. On the other hand, you would choose multiprocessing when dealing with CPU-bound tasks, as it allows true parallelism by utilizing multiple CPU cores.