The boundaries between formal and informal language are often blurry. Misunderstandings can arise when a language student or interpreter does not choose correctly when speaking a language that distinguishes between formal and informal personal pronouns. One runs a risk of being considered impolite on the one hand, or snobbish on the other.
The formal singular pronoun is used to express respect to an addressee, whether it is a superior, an older person, a business partner, or a new acquaintance. The informal pronoun, conversely, establishes a sense of closeness and trust among friends and relatives. There is a very special—even intimate—moment when the formal pronoun suddenly changes to its familiar form in the middle of the conversation; or there is a reverse effect of chilling distancing when the formal pronoun is uttered in place of the familiar. Interestingly, most European languages preserve the distinct forms of polite and familiar personal pronouns. In Modern English, however, the practice became largely obsolete.
A similar form of both formal and informal pronouns exists in almost every Indo-European language. Here are a few examples: