What is the cultural difference between the second person pronouns "Sie" und "Du" in spoken language?

Whilst both pronouns are widely used, usage varies between regions in Germany, Austria and Switzerland. Broadly speaking, "du" is taken to be informal and "Sie" is taken to be formal - however the usage of these varies depending on where you are. It is always safest to use "Sie" rather than "du", as using the informal pronoun in a formal situation may cause offence. Generally, "Sie" is used when speaking to someone you do not know, someone older than yourself, or someone who naturally requires respect - for example, with a doctor, with your friend's grandparents, or with your partner's family - or when talking to a teacher in a classroom.

"Du" is used for situations such as talking to friends or family.

If in doubt, you should always use "Sie" - whilst you may be too formal, you are unlikely to offend anyone by using the wrong form.

"Du" and "Sie" also require different verb forms - "Sie" takes the same conjugation as "wir", and "du" has its own conjugation (e.g. du hast).