du, sie
German is a T-V-language, this means, for 2nd person ("you" in English) there are two different forms. One form is used when talking to children, family members and good friends, the other form is used when you talk to adult strangers, to officers or to customers.
The non-formal child-and-friend-form uses the pronoun »du«:
Du siehst gut aus. = You look fine.
The formal adult-strangers-form uses the pronoun »sie«:
Sie sehen gut aus. = You look fine.
But the way to build this formal kind of 2nd person singular is grammatically identical to 3rd person plural ("they" in English). (Which btw is also the etymological root of this form: You honor the person to who you talk by talking as if they was two or more persons, and you don't offend the person by direct addressing. You talk like you would talk about absent persons. Old English also had this T-V-distinction, but lost it over the centuries.)
Sie sehen gut aus. = They look fine.
To confuse you even more, there also is another »sie« in German:
Sie sieht gut aus. = She looks fine.
This is 3rd person singular female, but as you can see, it is built in a different way: Look at the verb. In the formal form of 2nd person singular it is »sehen«, but now it is »siehst«.
And all of this kinds of »sie« exist not only in nominative case (as shown above), but also in accusative case:
- Ich sehe dich. = I see you.
- Ich sehe Sie. = I see you.
- Ich sehe sie. = I see them.
- Ich sehe sie. = I see her.
- Non-formal form of 2nd person singular.
- Formal form of 2nd person singular.
- 3rd person plural.
- 3rd person singular female.
Capitalization
I said, that the formal form of 2nd person singular is identical to 3rd person plural, but that is not absolutely correct. There is a subtile difference that exists only in written language (you can't hear it in spoken German): The pronoun »sie« is capitalized when it is used in the formal form of 2nd person. I already did it in my accusative examples:
Ich sehe Sie. = I see you.
Ich sehe sie. = I see them.
Note, that the non-formal form of 2nd person singular (»du«) may or may not be capitalized:
Ich sehe Dich. = I see you.
Ich sehe dich. = I see you.
Or in nominative case:
Wo bist du? = Where are you?
Wo bist Du? = Where are you?
You can freely decide if you write »du« or »Du«, but within one document you should always use the same form.
Plural
I've been talking about singular only until now. I just showed, that the formal form of 2nd person singular is identical to 3rd person plural, but I did not talk about 2nd person plural. I do now:
- Wo seid ihr? = Where are you?
- Wo seid Ihr? = Where are you?
- Wo sind Sie? = Where are you?
- (Wo sind sie? = Where are they? )
- Non-formal form of 2nd person plural, not capitalized.
- Non-formal form of 2nd person plural, capitalized.
- Formal form of 2nd person plural. Must be capitalized.
- (3rd person plural. Must be not capitalized.)
Some more examples:
- Jeder weiß, ihr seht gut aus. = Everybody knows, you look fine.
- Jeder weiß, Ihr seht gut aus. = Everybody knows, you look fine.
- Jeder weiß, Sie sehen gut aus. = Everybody knows, you look fine.
- Non-formal form of 2nd person plural, not capitalized.
- Non-formal form of 2nd person plural, capitalized.
- Formal form of 2nd person plural. Must be capitalized.