Facebook embeds non-visual tracking watermark in photos uploaded by users

Facebook embeds non-visual tracking watermark in photos uploaded by users. The IPTC (International Press Telecommunications Council) codes are metadata watermarks that Facebook adds to tag each user image with its own unique code. Once inserted they can be read later, used to trace back the owner of the image, to clarify copyright questions, and to identify which users are connected. For example, if an image is uploaded by one user on Facebook, and subsequently downloaded by a second user and reposted to a private WhatsApp group, Facebook can see that the two users share a common interest around this content. That data can be used to target advertising to both of them. Interestingly, Twitter strips the IPTC code from use photos when they are uploaded. Forbes