What are context managers and what are they used for?

Context managers in Python are constructs that manage resources, ensuring their proper opening and closing. They are used with the keyword with to automatically perform actions upon entering and exiting a block of code.

The main purpose is to guarantee that resources (files, network connections, locks, etc.) are released even if exceptions occur.

Example of using a context manager to work with a file:

with open('file.txt', 'r') as f:
    data = f.read()
# the file is automatically closed after exiting the block

You can create your own context managers by implementing the __enter__ and __exit__ methods in a class.