While the distinction is very old - a spear is anti-personnel, while a catapult is of more use against buildings than individuals, the large-scale development of military technology in the 19th and 20th centuries has made the concept a key consideration in design. For instance, an anti-personnel landmine will be designed not to explode when a vehicle rolls over it, and will explode into small and sharp pieces of shrapnel that tear flesh but have no effect on metal surfaces.
In general, anti-personnel weapons are designed to exploit human frailty; the general delicacy of the human frame, the need for breathable air and drinkable water, susceptibility to fire and radiation, and so forth. Anti-personnel weapons need not muster great force, as in the case of armor-piercing shells, but instead may spread smaller and slower projectiles over a larger area.
Notable anti-personnel weapons include the neutron bomb.