I was talking to
mooch about his trip to France, and meeting a man who, after some fun (and I wish I had the sentence -- help me out here), was being referred to by said man with tu, as opposed to vous when they met. This, in French, is called tutoyer, and can be interpreted in English as "to get to know someone better" -- it shows a level of politeness or familiarity that isn't really reflected in English use. Most languages in Europe have references to people in the second person with terms to show politeness (Spanish has usted instead of tú, and in the plural (at least in Spain) ustedes instead of vosotros; German uses Sie in place of the singular informal Du and the plural informal Ihr; Greek has εσύ, esy, vs. the formal εσείς, eseis). Often these new pronouns are accompanied with third-person forms of the vebs (in Spanish, comes, "You eat" vs. usted come, "You (formal) eat and el come, "He eats"; German and Du bist vs. Sie ist, "You are" (formal and informal, respectively). These uses, however, aren't always adhered to everywhere a language is spoken; most of Latin America uses ustedes (and the third person plural verb) instead of vosotros (certain countries also use an ALTERNATE second-person singular, vos), and frequently in Brazlian Portuguese você (the formal "you") replaces the informal tu; even when tu is used, the third person verb often goes along with it, meaning that formality may or may not exist depending on which version of a language someone is speaking.
There's more than just formal and informal -- some languages have more than one "level", as seen in the Hindi use of तू, tū (VERY informal, like with children), तुम (tum, somewhat of a middle ground) and आप, āp (formal). Japanese not only has multiple pronouns in the second person for showing varying degrees of distalness or familiarity -- あなた, anata, is a standard distal "you", for example, whereas 手前, temae, is more akin to a reference to someone before you start beating on them -- it's not the only way to show politeness and, indeed, nowhere near the most common. FIRST-person pronouns are more frequently used to show a relationship to the speaker (私, watashi is a distal form of "I", whereas 俺, ore, is far more informal and can sometimes be seen as "vulgar" in certain situations), and references to people are more frequently that person's name (or position) rather than a second-person form. Suffixes are then added to show relationships or politeness -- 藤本さん, Fujimoto-san, is far more polite than, say, using either -kun, which would imply a closer relationship (say, coworker or classmate), or nothing at all, which implies more intimacy. Verbs also have polite forms and even humble forms -- だ, da, "it is", can be made formal (です, desu), and go even further (でございます, gozaimasu), and can go further to show respect (でいらっしゃる, irassharu), and other verbs can be made to show that one is humbling HIMSELF -- 申し上げる, moshiageru, is a humble form of 言う, yuu, "to say". This leads to a gradient of levels of politeness that one can achieve with someone in the language -- using too familiar of a speech with someone can be seen as insulting or disparaging, whereas too formal of a tone can be seen as condescending. That being said, one can use multiple forms with someone; I'm on familiar terms with Fujimoto-sensei, but if I feel I'm inconveniencing him or asking for something, I tend to be more polite.
Some languages, however, are void of such levels of politeness -- there is nothing necessarily rude in Hebrew, for example, with saying, "אני רוצה את הספר הזה", Ani rotseh et hasefer haze, "I want that book." One could attach בבקשה, bevakasha, or use a more literal "I would like," הייתי רוצה, hayiti rotseh, but it's not needed, and Israelis as a result tend to sound more "blunt" when speaking in English if they're literally translating mentally what they want to say from Hebrew. And indeed, in many other languages, even if there's no direct statement of politeness, this isn't to say that there's no way to SHOW politeness in a language -- this is done usually by softening statements by making them less direct ("I would like" vs. "I want").