A Dropship is a flying vehicle used to transport Infantry, supplies, or sometimes even vehicles. Compared to ground transports like APCs, dropships are faster and capable of bypassing most terrain obstacles, but often have less carrying capacity and protection than similar sized APCs. Although primarily used to carry troops from orbiting Capital ships to a planet's surface, they can also be used in battle as troop transports and attack craft.
In addition to carrying infantry, most dropships are equipped with weapons to defend themselves from attack and provide covering fire for their infantry once they disembark. Extremely well-armed dropships are often referred to as Gunships, and are formidable combatants even when they're not carrying troops. Many dropships are equipped with engines which can swivel to face downward, allowing them to hover in place so that their infantry can climb on and off more easily. Other dropships carry their troops in a detachable platform or compartment, allowing them to deploy their troops without having to slow down to land, and without exposing them to enemy fire. Still others simply use some form of anti-gravity Teknology to hover and land.
Since dropships are usually faster than APCs and capable of bypassing terrain obstacles more easily, commanders often use dropships to transport elite units such as Ninjas, Heavies, or Heroes. The dropship's speed allows it to quickly deliver them to wherever they are most needed on the battlefield, to repel an enemy's attack or exploit a weak point in their defenses. Dropships' ability to bypass terrain features lets cunning generals use them to deploy troops past terrain that would stop ground-based units, such as mountains, rivers, or the walls of fortresses. The main limitation of most dropships is their low transport capacity: a shipload of troops usually won't be enough to overwhelm a ground-based force. To counter this problem, you can either put elite units aboard your dropship, or have the dropship's infantry jump off, attack, and jump back onto the ship before a counterattack can destroy them.