from the help: :h syntax-reset
If you have changed the colors and messed them up, use this command to get the defaults back: >
:syntax reset
It is a bit of a wrong name, since it does not reset any syntax items, it only affects the highlighting.
This doesn't change the colors for the 'highlight' option.
so this tells us: it does not reset any syntax items and it doesnt
change the highlight
option
what does it do?