The pronouns ich (not capitalized) "I," wir "we," and sie "they" are used almost identically to the same pronouns in English. All three are used by both male and female speakers, and the plural wir "we" and sie "they" can refer to groups of males, females, and mixed genders.
The second person pronouns du and ihr, which are both "you" in English, are familiar forms. Familiar forms should be used only with family members, close friends, children, peers, and animals. For example, du isst "you are eating" can be said to a best friend or a baby cousin. The familiar du is also used pejoratively by the speaker to show superiority or express contempt.
The second person singular and plural pronoun Sie (always capitalized) is the formal or polite form of "you." Formal forms are always used with strangers, casual acquaintances, superiors, professional colleagues, people with formal titles, and others not well know to the speaker. For example, Sie schreiben "you are writing" can be said to a boss at work or a stranger at the library.
The use of the third person singular pronouns er "he, it," sie "she, it," and es "it" is determined by the grammatical gender of the noun it replaces rather than biological or social gender. Both the masculine der Tag "day" and der Onkel "uncle" are replaced by the masculine er, the feminine die Woche "week" and die Tante "aunt" by the feminine sie, and the neuter das Buch "book" and das Mädchen "girl" by the neuter es.
The impersonal man in German corresponds to the impersonal one in English. For example, the German pun man ist was man isst translates to the English idiom "one is what one eats." The use of the impersonal man is much more common in German than the use of the impersonal "one" in English.
The difference in person (second, third) and number (singular, plural) between the different forms of sie/Sie is distinguished by the form of the verb in the sentence, the context of the sentence, and the capitalization in writing.
