Apartment handover (Wohnungsabnahme).
Joint walk-through by tenant and landlord at move-in and move-out, with a written record.
The Wohnungsabnahme is the joint walk-through by tenant and landlord (or their property management) at move-in and move-out. It documents the state of the apartment in writing: walls, floors, appliances, doors, windows.
At move-in: any defect you don't record will be considered your responsibility at move-out. Photograph everything. Insist on a written record.
At move-out: same in reverse. Damage corresponding to normal wear-and-tear is the landlord's responsibility. Self-inflicted damage (hole in wall, burn marks, water damage) is deducted from the deposit.
Important: if the landlord refuses to record a defect? Write to them by registered letter immediately describing the state. Legally counts as a record.