.pyc .pyd .pyo Extensions in Python

• .py : usually the input source code you wrote.
• .pyc : is the bytecode compiled. If you import a module, Python will build a *.pyc file that contains bytecode to make it easier and faster
• .pyo : is a * .pyc file that was created with optimizations enabled (-O)
• .pyd : is basically a Windows DLL file .
• .pyw : Python script for Windows. It runs with pythonw.exe
• .pyx : Cython font to be converted to C / C ++
• .pxd : Cython script which is equivalent to a C / C ++ header
• .pxi : MyPy stub
• .pyi : stub file ( PEP 484 )
• .pyz : Python script file ( PEP 441 ); Contains scripts compressed Python (ZIP) in binary form after the Python standard script header
• .pywz : Python script file for MS-Windows ( PEP 441 ); Contains scripts compressed Python (ZIP) in binary form after the Python standard script header

Fonts in Bill Lynch SO Answers and Devyn Collier Johnson .

.py is usually the code written by yourself.

.pyc is compiled binary code. If you import a module, Python will generate a * .pyc file that contains the binary to facilitate (and be faster) to import the same module again.

.pyo equal to file .pyc but created when optimizations (-0) were linked.

.pyd is basically a windows dll file (more info HERE )

If you want more infos about the difference between .pyo and .pyd, check out here

Source: SO gringo