Nick:
...
> I haven't heard it articulated before why 80 (or indeed 72) columns
> is a good thing. I guess in my case it's because I usually use a
> laptop screen with largeish letters, but also just for the sake
> of standardization. My feeling is there must be a limit, so the
> limit should be defined. The value is unimportant, if we could all
> agree on 132 characters (does anyone remember dot matrix printers
> that could print 80 columns normal size, 132 condensed?) , then that
> would be okay with me, but the consensus does seem to be 80.

The 80 chars line length comes from what was common on punched cards:
https://en.wikipedia.org/wiki/Punched_card
The 132 limit is from the VT100 terminal:
https://en.wikipedia.org/wiki/Vt100

You can use whatever line length you conveniently can read without
loosing the sense of what the current line is.

If you want to share code with someone else you should consider
others capability in that sense.

For more about the topic, see:
https://knox.codes/posts/line-length-limits
https://hilton.org.uk/blog/source-code-line-length
https://courses.cs.washington.edu/courses/cse122/25wi/resources/code_quality/
Similar for texts:
https://en.wikipedia.org/wiki/Line_length
https://baymard.com/blog/line-length-readability

or just search the net.

Regards,
/Karl Hammar