They don't for standard picture but they do embbed their own metadata https://iptc.org/news/what-does-facebook-do-with-your-photo-metadata/ https://iptc.org/ne

They don't for standard picture but they do embbed their own metadata https://iptc.org/news/what-does-facebook-do-with-your-photo-metadata/ https://iptc.org/news/what-does-facebook-do-with-your-photo-... https://www.carlseibert.com/facebooks-hidden-metadata-codes/ https://www.carlseibert.com/facebooks-hidden-metadata-codes/ You may be thinking of PhotoDNA which is used for different purposes https://www.microsoft.com/en-us/photodna https://www.microsoft.com/en-us/photodna