There are three levels of politeness in Bengali.
1) Respectful (to strangers/elders): Ami (I), Apni (you), Tini/Uni/Ini (he/this person)
2) Polite without respect (to the peers of same level/lovers): Ami (I), Tumi (you), Se (he)
3) Close (to close friend) or impolite (to subordinate): Ami (I), Tui (you), O (he)