IPTC
The International Press Telecommunications Council (IPTC) is a consortium of news agencies around the world - one of its goals is to develop and maintain technical standards. The IPTC defined a set of photo metadata standards for images that is almost universally accepted among photographers. These metadata standards were part of the broader standard known as the IPTC Information Interchange Model (IIM) created in the 1990s.
Although the IPTC header information has been mostly superseded by XMP, an IPTC core schema and an extension schema are available for XMP. In image programs, both XMP and IPTC properties are synchronized.