The precise origin of the military hand salute is unknown. More than one purported stories attempts to explain the beginnings of the hand salute tradition.
The first explanation of the hand salute comes from an early, long-established military custom for subordinates to remove their headgear in the presence of their superiors. This gesture was gradually transformed from removing the head gear to simply grasping the head gear; perhaps transforming to what it has become today.
A second story claims that the hand salute is based off of an early greeting ritual. In this greeting ritual, one person would raise their hand either for acknowledgment, or so they could show that they did not have a weapon to use against the person they were greeting.
Another, more legendary, tale explains that the hand salute is a descendant from early times when a medieval knight would raise the visor of his helmet to reveal his identity as a courtesy on the approach of a superior.