The Medal of Honor is the highest military decoration awarded by the United States government. It is bestowed on a member of the United States armed forces who distinguishes him- or herself "conspicuously by gallantry and intrepidity at the risk of his [or her] life above and beyond the call of duty while engaged in an action against an enemy of the United States." Because of the nature of its criteria, the medal is often awarded posthumously.

The Third Infantry Division has received 61 medals, more than any other Division in the Army.

Members of all branches of the U.S. military are eligible to receive the medal, and each service has a unique design with the exception of the Marine Corps and Coast Guard, which both use the Navy's medal. The Medal of Honor is often presented personally to the recipient or, in the case of posthumous awards, to next of kin, by the President of the United States. Due to its high status, the medal has special protection under U.S. law.

The medal is frequently called the Congressional Medal of Honor, stemming from its award by the Department of Defense "in the name of Congress."

The first formal system for rewarding acts of individual gallantry by American Soldiers was established by George Washington on August 7, 1782, when he created the Badge of Military Merit, designed to recognize "any singularly meritorious action." This decoration is America's first combat award and the second oldest American military decoration of any type, after the Fidelity Medallion. Although the Badge of Military Merit fell into disuse after the American Revolutionary War, the concept of a military award for individual gallantry by members of the U.S. armed forces had been established. In 1847, after the outbreak of the Mexican-American War, a Certificate of Merit was established for Soldiers who distinguished themselves in action. The certificate was later granted medal status as the Certificate of Merit Medal.

Early in the Civil War, a medal for individual valor was proposed by Iowa Senator James W. Grimes to Winfield Scott, the Commanding General of the United States Army. Scott did not approve the proposal, but the medal did come into use in the Navy. Public Resolution 82, containing a provision for a Navy Medal of Valor, was signed into law by President Abraham Lincoln on December 21, 1861. The medal was "to be bestowed upon such petty officers, seamen, landsmen, and Marines as shall most distinguish themselves by their gallantry and other seamanlike qualities during the present war." Secretary of the Navy Gideon Welles directed the Philadelphia Mint to design the new decoration. Shortly afterward, a resolution of similar wording was introduced on behalf of the Army and was signed into law on July 12, 1862. This measure provided for awarding a Medal of Honor, as the Navy version also came to be called: "to such noncommissioned officers and privates as shall most distinguish themselves by their gallantry in action, and other Soldier-like qualities, during the present insurrection."

Although it was created for the Civil War, Congress made the Medal of Honor a permanent decoration in 1863. In total 3,493 medals have been awarded to 3,450 different men and one woman. Nineteen men received a second award: 14 of these received two separate medals for two separate actions, and five received both the Navy and the Army Medals of Honor for the same action. Since the beginning of World War II, 867 Medals of Honor have been awarded, 528 posthumously. In total, 621 had their medals presented posthumously. A total of 2,418 Army members have received Medal of Honor.