Did you know that Russians are very careful about how to talk to different people in different situations? The Russian language itself forces us to do so, because every time you refer to a person you need to choose – should I say "ТЫ" or "ВЫ", "КАК ВАС ЗОВУТ?" or "КАК ТЕБЯ ЗОВУТ?", "КАК У ВАС ДЕЛА?" or "КАК У ТЕБЯ ДЕЛА?". Apart from lots of other language formulas of politeness, even imperative verbs fall into two groups: formal imperative, that end in -ТЕ (извиниТЕ, скажиТЕ, дайТЕ) and informal (извини, скажи, дай).
Situations you must be formal
- When you meet a person for the first time it's better to be formal. Though if it's a friend of your friend or someone drunk in a bar you might want to be looser;)
- In a business meeting
- At education establishments with teachers
- At any organization, company, even in a shop! Please, do not say "Привет! Как дела?" to a cashier in a supermarket. That's really weird:)
- When talking to an elderly person, even if you know him/her quite well
- When talking to people that occupy a higher status position than you, for example, to officials, police officers, directors and etc.
So, every time when you are not sure, which one to use – ТЫ or ВЫ – better use ВЫ. But as soon as the person you are talking to starts saying ТЫ to you, feel free to do the same thing:)