Thank you for your question.
If you are planning to travel just for a (short-term) visit, you don't have to inform the immigration office (Ausländerbehörde). Please note, however, that you would have to discuss with them any other purpose (studying, nursing a family member etc.) than visiting/travelling. In general, a temporary residence expires if you have left Germany for more than 6 months.
In case you are receiving social money (i.e. by the jobcenter), you have to apply for your travels at the respective auhtority. The jobcenter is usually granting up to 3 weeks per year.
I hope this helps and please don't hesitate to get back to us with any further questions.
All the best,