A T-V distinction, in sociolinguistics, is used to describe the situation wherein a language has pronouns that demonstrate varying levels of respect, distance, courtesy, familiarity, or insult. The name "T-V distinction" derives from the common initial letters of several of these terms in Romance languages.

Here are some examples of second-person pronouns in languages with T-V distinctions:

  2nd person singular informal 2nd person singular formal 2nd person plural informal 2nd person plural formal
French tu vous vous vous
Peninsular Spanish usted vosotros (masc.)
vosotras (fem.)
ustedes
Catalan tu
vós (only to elder people)
Vós (to God)
vostè vosaltres vostès
Italian tu Lei voi voi or Loro
German du Sie ihr Sie
Greek esy eseis eseis eseis
Dutch jij (Netherlands)
gij (Belgium)
u or U jullie u or U
Swedish du ni or Ni ni ni or Ni
Danish du De I I
Finnish sinä te te te
Slovenian ti vi vi vi
Polish ty Pani (to a woman)
Pan (to a man)
wy Państwo (general)
Panie (to women)
Panowie (to men)
English thou/thee (archaic) ye/you ye/you ye/you
Welsh ti chi or chwi chi or chwi chi or chwi
Yiddish du ir ir ir
Ubykh wæghwa syæghwa syæghwa syæghwa
!Kung a i!a i!a i!a
Basque hi (very close or dialectal), zu zu, berorrek (very respectful) zuek zuek
Romanian tu dumneavoastra voi dumneavoastra

Some languages have even more gradations. For example, Vietnamese has different pronouns for 'sir', 'ma'am', 'older brother', 'younger brother', 'older sister', 'younger sister', 'uncle', 'aunt', and on and on, although these do not affect verb morphology.

The pronouns in the table above come complete with differing verb morphology; in French, the respectful vous takes plural verbs (but not adjectives), and in Spanish and Italian, but not German, the respectful form causes verbs to be conjugated in the third person. In the case of Spanish, this is because the form usted evolved from the title vuestra merced (your grace) which naturally took the third person.

Catalan vos follows the same concordance rules as the French vous (verbs in 2nd person plural, adjectives in singular), and vostè follows the same concordance rules as the Spanish "usted" (verbs in 3rd person). Vostè originated from vostra mercè as a calque from Spanish, and replaced the original Catalan form vos.

It can often be quite confusing for an English speaker learning a language with a T-V distinction to correctly assimilate the rules surrounding when to call someone with the formal or the informal pronoun. Close friends, of course, are tu and venerable old ladies are vous, but there is a wide grey area in the middle. Even that is not universally true: in some parts of Latin America (for example, in Colombia), tu is almost never used, not even with close friends or relatives, which are usted. Students are often advised to err on the side of caution, i.e. the formal; however, in the wrong situation this risks sounding snobby or at least riotously funny. English speakers may be helped by reminding themselves that the difference is comparable to using first name or last name when speaking to someone; however the boundaries between formal and informal language differ from language to language, and most languages use formal speech more frequently, and/or in different circumstances, than English. And in some circumstances it is not unusual to call other people by first name and the respectful form or the reverse, e.g. German shop employees often use these constructs if a customer is present.

In Greek, συ was originally the singular, and υμεις the plural, with no distinction for honorific or familiar. Paul addressed King Agrippa II as συ (Acts 26:2). Later, υμεις and ημεις ("we") became too close in pronunciation, and a new plural εσεις was invented. The ε of εσυ is a euphonic prefix.

English formerly had a distinction between thou (informal) and you or ye (formal). Some groups such as the Quakers that advocate "plain speech" used the "thou" form with everybody, a custom some carry on to this day, although "thou"'s passing out of most dialects of English, including the standard, has made it more symbolic than anything.

Even within languages they differ between groups (older people and people of higher status tending to both use and expect more formal language) and between various aspects of one language. For example, in Dutch, U is slowly coming into disuse in plural, and thus one could sometimes address a group as jullie when one would address each member individually as U. In Latin American Spanish, the opposite change has occurred - having lost vosotros, Latin Americans address all groups as ustedes, even if the group is composed of friends whom they would call .

French has verbs - tutoyer and vouvoyer - meaning to call someone tu or vous. (Spanish has the verb tutear, Catalan has the analogous verb tutejar). In German there are the verbs duzen and siezen.

In Germany, an old but by no means extinct custom involves two male friends formally splitting a bottle of wine to celebrate their deciding—always at the suggestion of the elder of the two—to call one another "du" rather than "Sie."

In Denmark, the use of the formal forms of address has diminished significantly over the last twenty years. Although the "De" form is still used in certain contexts, it is much more common now for people to address virtually all people with the familiar "du".

In Swedish there has been a marked difference between usage in Finland-Swedish compared to in Sweden. While the form "Ni" (noted as formal above) has remained the common respectful address in Finland-Swedish, it was until the 1960s considered somewhat careless, bullying or rude in Sweden, where addressing in 3rd person with repetition of name and title was considered proper and respectful. After that the usage swiftly changed in Sweden, and the 2nd person "du" (noted as informal above) came to dominate totally (although the King still used to be addressed in 3rd person), until recently when in the late 1990s a usage resembling that in German, Finnish or Finland-Swedish has become popular among the youngest adults.

In Ubykh, the T-V distinction is most notable between a man and his mother-in-law, where the plural form syæghwa supplants the singular wæghwa very frequently, possibly under the influence of Turkish. The distinction is upheld less frequently in other relationships, but does still occur.

A distinction quite similar to the T-V distinction appears in Japanese in the use of the "plain" and "polite" conjugations of verbs and adjectives. In general, the plain form is used when speaking to family, close friends, and social inferiors, and the polite form otherwise.