質問への返事の中に、
1.polite
2.formal
3.Informal
4.casual
5.colloquial
などが書かれていますが、それぞれどのような相手に対して、または、どのような時に使う言い方の事を指しますか？

例えば、
ビジネスの場面で使う時
初対面の相手と話す時
友達と話す時
家族と話す時

辞書には、
polite=丁寧な、礼儀正しい
formal=正式の、公式の、形式ばった
と、書いてありますがどちらがより丁寧な表現になるのでしょうか？
どのくらい丁寧な表現なのでしょうか？
「です・ます調」よりもっと丁寧な表現を指しますか？

Vedi una traduzione

English doesn't have strict levels of politeness, so these definitions will be different for every English speaker.
In general, I think of the politeness levels like this:

1. Polite:
- talking to strangers, customers, bosses, teachers
- indirect, "soft" expressions like "Could you ~?" or "Would it be possible to ~?"
- calling people by their title, like "sir" or "professor"

2. Formal:
- writing a news article, a report, business e-mails
- no contractions
- using many words from Latin and Greek (for example, "start" → "commence")

3: Informal/casual:
- the general way of speaking and writing, except for the special situations where you need to be polite or formal

4: Colloquial:
- very casual situations, like speaking to friends or chatting online
- many non-standard contractions: "I'mma" (= I will), "gonna" (= going to), "kinda" (= kind of = somewhat)