Like articles and adjectives, pronouns in German vary according to gender and case. But this time it should be slightly more familiar, as English has kept some of these distinctions too. Here are the personal pronouns in English, which hopefully look familiar:

As you can see from the table below, German pronouns are a little more complicated. Three important things to notice:

1. German pronouns often distinguish between the accusative and the dative case, while English pronouns never do. Old English did have this distinction, but even by the time of Chaucer it was gone (e.g. thee was both accusative and dative).
2. German has a second person plural (ihr) that’s different from the singular (du); English uses "you" for both, except in casual/regional plurals like “y’all” or “you guys."
3. German adds a formal “you” (Sie), which is both singular and plural. These “Sie” forms share the same conjugation as the third person plural, but are capitalized.

The genitive forms (last row) are grayed out because they're almost never used. We've included them mainly because they give you the stems of the possessive articles (mein, dein, sein, etc.) that are used instead (see II.3). Indeed, saying "der Hund meiner" instead of "mein Hund" would be just as awkward as saying "the dog of me” in English.

When to use the Sie form rather than du or ihr is one of the most common questions for German learners, and there's no simple answer. Like most “proper” forms of address (“sir/ma’am” in English, vous in French) it’s no longer used in every situation where the teachers and textbooks suggest that it is. However, it’s still important to use Sie with police officers (in Germany this is actually the law) and other authority figures. It’s also polite to use it with anyone in a service position, like waiters, clerks or salespeople.

After that, it’s largely a matter of familiarity and age – both the absolute age of the person you’re talking to (older people are more likely to expect Sie), and their age relative to yours. It can be about the setting, too: sometimes the same two people will address each other with Sie in the office and du in the bar after work. It’s also about the tone you’re trying to adopt, and sometimes even a touch of politics; for example, it was kind of a Hippie thing to use du with everyone as a statement of egalitarian values. Anyway, you should never use Sie with children, but otherwise it’s safer to fall back on Sie whenever you’re not sure.