What is a compiled file with the extension .pyc in Python?

A file with the .pyc extension is a compiled Python bytecode. When you run a .py script, the Python interpreter compiles the source code into bytecode, which is then executed by the Python virtual machine.

To speed up subsequent runs, the bytecode is saved in a .pyc file within the __pycache__ directory. On a subsequent run, the interpreter can use this file if the original .py file has not changed.

Thus, .pyc is an intermediate representation of the code that helps to accelerate the loading and execution of Python programs.

Example structure:

my_module.py       # source code
__pycache__/
    my_module.cpython-38.pyc  # compiled bytecode for Python 3.8