From the US Cybersecurity and Infrastructure Security Agency:
Traffic Light Protocol (TLP) is a system of markings that designates the extent to which recipients may share potentially sensitive information. Though the protocol has been in use for nearly two decades by the incident coordination and response community, the Forum of Incident Response and Security Teams (FIRST) formally published TLP 1.0 in August 2016; this version, TLP 2.0, was published in August 2022.