The Integrated Authority File (Gemeinsame Normdatei or GND) – till 2012 Name Authority File (Personennamendatei or PND) – is a register of unique identifiers for people (GND, type p), maintained by the German National Library in collaboration with European libraries and archives. It is used by Wikipedia and the Commons:Bundesarchiv project to identify individuals and to link to literature by and about these individuals.
To add a GND-link to a Commons picture, enter the following template, adapted to the person in question:
The example is for Carl Peters (1856–1918), a German colonial officer. The number is the GND number, followed by surname and given name.
You can retrieve the GND number on the page of the Online GND (OGND) search page. If there are various people with similar names, choose the correct person.
See de:Hilfe:GND for more information on what the GND is and how it was used on the German language Wikipedia, respectively.