The discussion revolves around notes on non-abelian local gauge invariance in field theories, particularly focusing on Yang-Mills theory. The author reflects on their utility for students studying the subject, despite being written 20 years ago. Corrections to the notes are provided, addressing issues stemming from the conversion from Math-Type to LaTeX, specifically regarding equation references. The notes are acknowledged as challenging due to their direct approach to non-abelian Lie groups. Overall, the content aims to support learners in grasping complex concepts in gauge theory.