2017
Proper RFC 4122 UUIDs as GUIDs in WordPress
UUIDs (Universally Unique IDentifier), also known as GUIDs (Globally Unique IDentifier), is a string that identifies a piece of information in computer systems. WordPress use GUIDs to identify each individual post, but use URLs (kind of) for GUIDs, and thus does not follow the standard definition (RFC 4122) of a UUID (or GUID).