For which purposes is a horn allowed to be used in built-up areas?

In built-up areas in Germany, using the horn is only permitted as a warning signal to alert others to dangers or to prevent an accident. It is not allowed to use the horn for overtaking or for calling attention without a traffic-related reason. Your answer is correct, because in towns and cities, the horn should only be used to warn others of danger. This helps reduce unnecessary noise and keeps the use of the horn focused on safety.