Marine Corps Core Values
Honor — Integrity, responsibility, and accountability. The quality of maturity, dedication, trust, and dependability that commits Marines to act responsibly, be accountable for their actions, and fulfill their obligations. Courage — The mental, moral, and physical strength to do what is right, in the face of fear, and to adhere to a higher standard of personal conduct. Commitment — The spirit of determination and dedication that leads to professionalism and mastery of the art of war. The promise or pledge to complete a worthy goal by worthy means.
What it actually means
Honor, Courage, Commitment. The same three words the Navy uses — the Marine Corps is part of the Department of the Navy — but the Corps drills them as its own identity from the first day at the depot. In practice these are the words a Marine gets measured against, and "Commitment" is the one the Corps leans on hardest: the job is mastery, not participation.
Where it came from
Adopted as the Marine Corps’ formal core values, shared with the Navy as the Department of the Navy’s values. They are foundational to recruit training at Parris Island and San Diego.
U.S. Marine Corps — reference