In medieval Europe, fealty was sworn by the obligated person (vassal) to a person of rank (lord). The most usual form had the vassal kneeling and placing his hands between the hands of the lord. The vassal pledged support (often, military and financial) and faithfulness, while the lord often responded with a corresponding oath of protection (and, often, a grant of land called a fief). This ceremony is thought to date back to, at least, 7th-century France.
The term is also used by English speakers to refer to similar oaths of allegiance in other cultures, as with Japan prior to about 1500.