Item 1: Know which version of Python you’re using

Notes

Python has several different versions all in various states of maintenance
Python 2 is the previous major version
- No longer supported
Many Operating Systems have multiple python versions installed by default
However the default meaning of python (the command to run python) is ill-defined
- Typically an alias for python 2.7
  - May be an older version of python 2 though
  - Or even python 3
- On systems where python 2 is not installed, then the command may error
  - This happens on my machine
```
  $ python --version
  Command 'python' not found, did you mean:
      command 'python3' from deb python3
      command 'python' from deb python-is-python3
```
Python 3, the new and currently developed major version is usually found under the command python3
On my machine
```
  $ python3 --version
  Python 3.12.3
```
Alternative run times like PyPy have their own run commands
I use uv which is a python version manager
- To run a uv managed python version my command is
```
  uv run [python3.X]
```
You can inspect the python version at run time using the sys module

import sys

print(sys.platform)
print(sys.implementation.name)
print(sys.version_info)
print(sys.version)

linux
cpython
sys.version_info(major=3, minor=14, micro=3, releaselevel='final', serial=0)
3.14.3 (main, Feb  4 2026, 13:50:59) [GCC 13.3.0]

Python 3’s minor versions update relatively often
- These add new features, deprecate or remove old ones
- The Release Notes are the best place to keep track of the updates
There is also constant evolution of community packages

Python 3 is the sole actively maintained and developed python version
It can be unclear what python is installed on a computer
- Use --version or sys to verify