Formal:
* आप (aap): This is the most formal way to address someone, used for showing respect to elders, strangers, or people in positions of authority.
* तुम (tum): This is a more informal form of "you" used for friends, family members, and people you are close to.
Informal:
* तू (too): This is the most informal form of "you" and is generally used only with very close friends or family members.
The choice of which word to use depends on the social context and the relationship between the speaker and the listener.