UML is a visual language for describing software systems, created by the Gang of Four at Rational Software (a company acquired by IBM).
https://en.wikipedia.org/wiki/Unified_Modeling_Language
[https://www.visual-paradigm.com/guide/uml-unified-modeling-language/what-is-uml/]https://www.visual-paradigm.com/guide/uml-unified-modeling-language/what-is-uml/)