Question

When should you use usted and when should you use tu? (Spanish)

Answer 1

both r used for" you"
usted is used to show formality
tu is used when u are talking with a person of same age or same educational qualifications(class)
PLZ mrk as BRAINLIEST

Answer 2

"Usted" is formal and "tu" is informal.

It is similar to "Aap" and "tum" in Hindi.

For friends and close relatives with similar strata you can use "tu", whereas unknown, respectable, seniors  you can use "usted".