You – tú (informal) and usted (formal)
(Pronounced too and oo-stehd)
To remember that you is pronounced too or oo-stehd (tú/usted) in Spanish, use the following mnemonic:
I asked you to come to the cinema with me, but you brought your brother too (tú), who instead (usted) of letting us sit together, sat between us.
Note: In South America, 'usted' isn't formal, it is the normal word for 'you'.