Manners are the way somebody behaves towards other people. Good manners, mind your manners, table manners.
They are local and arbitrary and they matter anyway, because they signal attention to other people — which is why the specific rules change and the underlying point does not. Manners maketh man is the motto of Winchester College. Note manner in the singular, which means a way of doing something.
1nounmannersThe way somebody behaves towards other people.
“It's bad manners to talk with your mouth full.”
manners is social behaviour.