Possessive adjectives agree in gender and number with the noun they refer to, and they generally come after the article.
E.g.:
il mio libro /
my book
la tua borsa /
your bag
il suo quaderno / his/her notebook
le nostre macchine /
our cars
i vostri telefoni /
your phones
le loro giacche /
their jackets
The singular family nouns are an exception and there is no definite article:
Mio padre; tuo fratello; tua zia; mio nipote; etc.
Whereas in the plural we use the definite article:
i tuoi fratelli; le tue zie; i miei nipoti; etc.
