A birthday, a new apartment, an anniversary ... there are plenty of reasons to throw a party. If you want to invite people over for a party in Germany, you have to stick to some rules, especially if you live in an apartment building. Check the building rules about whether barbecuing on the balcony is allowed, for example. Noise has to be kept to a minimum from 10 p.m. to 6 a.m. Disturbances during the night can be reported to the police. If the police are called repeatedly, you may face a fine.
Are you planning a party? Then you should give your neighbors a friendly heads-up. The best way to do that is to put up a notice. You can include the date and time of the party, and perhaps even the occasion, and you can apologize in advance for the noise. But even advance warning doesn't mean you can have loud music going all night. It does give your neighbors a chance to prepare. Many neighbors are tolerant if parties don't happen too often. If you get on well with your neighbors, you can invite them to come. After all, joining the party is more fun than complaining about it!