What was a bow & arrow? Wel, to put it simply, it was a weapon (bow) used to fire a projectile (arrow) that pierces skin.
How were bow & arrows used? They were used for firing a lethal projectile across an area, providing more range than throwing a spear, and with less effort.
What kind of strategies were used, and why were they effective? The archers would stay as far away from the enemy as their range would limit them. They fired at the enemy in a rain of arrows while the soldiers charged in with their swords, shields and spears. They would stay back because they are ranged, and are more effective at hitting people that aren’t stabbing them. They are effective in large numbers because you can’t be very accurate, so with 200 arrows flying towards the enemy when they are all grouped up, they are sure to hit something.