“Public”

A group counts as "public" for the law: any class of the public or any community is included. So when conduct is directed at a particular class or community, it can be treated as an act against the public and public-offence provisions may apply.

Priya posts insulting messages aimed at members of her neighbourhood community. Since "public" includes any class or community, her messages are treated as directed at the public, so offences that require publication to the public can be invoked.