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I'm not sure we need to add a reference to setting the locale, since the text already says it's local aware.

While this may be obvious to a core CPython developer, it was not obvious to me or my friend, who is a Python trainer. We have each been using Python for many years. My friend routinely explores parts of the Python documentation to learn new things and share with the community. He found out about then option andshared it on Bluesky, mentioning that the thousands separator may be nothing in your locale. I was excited to try this because I use the comma in the format specifier all the time and sometimes when I teach or show code snippets using this in places that use a different thousands separator, I get asked about this.

When I tried then option, however, it didn't do anything on my machine, which I was shocked to see. I then read through the docs and couldn't see why it wouldn't work. Thestring module docs lack any reference to thelocale module, which at this point I didn't even know existed. I searched on the Internet to see how I could check if my locale was correct, which led me to thelocale module, and I was able to confirm it was set as I would expect. Since the locale was indeed set and the docs say thatn provides locale-aware formatting, I was confused why it wasn't working.

I searched some more to discover why it wasn't using a thousands separator for the format. This time Stack Overflow led me to the real reason behind it not working: I needed to set theLC_NUMERIC category. I seriously doubt that my friend and I are the only people that don't find this obvious, so I made a PR in the hopes that the next person can figure out how to get this working while reading the docs directly, instead of having to troubleshoot it for a while (or just assuming it doesn't work).