T–V distinction
The T–V distinction is the contextual use of different pronouns that exists in some languages, and serves to convey formality or familiarity. Its name comes from the Latin pronouns "tu" and "vos". The distinction takes a number of forms, and indicates varying levels of politeness, familiarity, courtesy, age or even insult toward the addressee. The field that studies and describes this phenomenon is sociolinguistics.