Medal of Honor, a history — ArmyTimes.com

The Medal of Honor is the United States of America's highest military honor, awarded for personal acts of valor above and beyond the call of duty. The medal is awarded by the President of the United States in the name of the U.S. Congress to U.S. military personnel only. There are three versions of the medal, one for the Army, one for the Navy, and one for the Air Force. Personnel of the Marine Corps and Coast Guard receive the Navy version. US awards including the Medal of Honor do not have post-nominals and while there is no official abbreviation, the most common abbreviations are "MOH" and "MH".

The Medal of Honor was created as a Navy version in 1861 named the "Medal of Valor", and an Army version of the medal named the "Medal of Honor" was established in 1862 to give recognition to men who distinguished themselves "conspicuously by gallantry and intrepidity" in combat with an enemy of the United States. Because the medal is presented "in the name of Congress", it is often referred to as the "Congressional Medal of Honor". However, the official name is "Medal of Honor", which began with the U.S. Army's version. Within United States Code the medal is referred to as the "Medal of Honor", and less frequently as "Congressional Medal of Honor"
https://en.wikipedia.org/wiki/Medal_of_Honor
http://www.cmohs.org/medal-history.php