Can you explain how context managers work in Python?

A context manager in Python is an object that defines the methods __enter__ and __exit__. When you use the with statement, Python calls __enter__ at the start of the block and passes its return value to the variable after the as keyword. When the block exits—whether normally or due to an exception—Python calls __exit__, passing exception details if any. This mechanism ensures that resources such as files, locks, or network connections are properly acquired and released. The built‑in open() function, for example, returns a file object that is a context manager. The contextlib module also provides decorators to turn simple functions into context managers.