In Mexican Spanish, usted is the formal word for “you.” The Diccionario del español de México, of El Colegio de México, says that it shows the respect owed to a person with whom one has no social acquaintance, and the courtesy and formality shown toward an authority or a person of different social position.
Tutear means to address someone as tú. The dictionary’s example reads: “Nos tuteamos desde jóvenes” (We have said tú to each other since we were young).
A 2026 study of educated speech in Mexico City, published in UNAM’s Anuario de Letras, calls tú the form of address of closeness, solidarity and confianza.