A hand is a prehensile, multi-fingered extremity located at the end of an arm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each "hand" and fingerprints remarkably similar to human fingerprints) are often described as having either "hands" or "paws" on their front limbs.
Hand-to-hand combat (sometimes abbreviated as HTH or H2H) is a lethal or non-lethal physical confrontation between two or more persons at very short range (grappling distance) that does not involve the use of firearms or other distance weapons. While the phrase "hand-to-hand" appears to refer to unarmed combat, the term is generic and may include use of striking weapons used at grappling distance such as knives, sticks, batons, or improvised weapons such as entrenching tools. While the term hand-to-hand combat originally referred principally to engagements by military personnel on the battlefield, it can also refer to any personal physical engagement by two or more combatants, including police officers and civilians.
Hand-to-hand combat is the most ancient form of fighting known. A majority of cultures have their own particular histories related to close combat, and their own methods of practice. There are many varieties within the martial arts, including boxing and wrestling. Other variations include the gladiator spectacles of ancient Rome and medieval tournament events such as jousting.
Military organizations have always taught some sort of unarmed combat for conditioning and as a supplement to armed combat. Soldiers in China were trained in unarmed combat as early as the Zhou Dynasty (1022 BCE to 256 BCE).
Despite major technological changes such as the use of gunpowder, the machine gun in the Russo-Japanese War and the trench warfare of World War I, hand-to-hand fighting methods such as bayonet remained common in modern military training, though the importance of formal training declined after 1918. During the Second World War, bayonet fighting was often not taught at all among the major combatants by 1944 German rifles were even being produced without bayonet lugs.