The World Day for Audiovisual Heritage on October 27, 2017 honors the heritage of audiovisual material humanity has collected during the last 100 years. The day had been proclaimed by the UNESCO in 2005 and aims to raise the public awareness of the importance of their audiovisual heritage. Audiovisual media is recorded or saved on different analog or digital storage mediums. But they are threatened by decay: there is for example no more complete version of the important silent movie “Metropolis” left on earth. The UNESCO advocates the conservation of that material as a part of the world cultural heritage.