"When do you use su and when do you use tu?"

Question

"When do you use su and when do you use tu?"

Answer 1

You use su [suyo] when you mean (3rd person) his, her, its, or your (usted- 2nd person, formal) or their (3rd person ellos, ellas or your- 2nd person, formal-ustedes).

You use tu [tuyo] when you mean your (tú - 2nd person, informal)

tu, su [tuyo, suyo] are possessive adjectives. (to modify singular nouns)

tus, sus, [tuyos, suyos] to modify plural nouns

su casa (la casa suya)= her house, his house, its house (the dog), their house, or your house, you all's house (you singular or plural, but formal)

tu casa (la casa tuya)=your house (informal you, singular)