STAPs are lightweight reconnaissance and patrol vehicles used by the battle droids of the Trade Federation army (and later, the Separatist Alliance). Incorporating repulsorlift technology, the STAP (single trooper aerial platform) is a slim, agile craft sporting a pair of blaster cannons. STAPs are often deployed as support vehicles in conjunction with larger craft.
STAPs are typically piloted by standard battle droids, whose humanoid frames can most easily control the lightweight vehicle. STAP patrols are usually assigned recon, security and "mopping up" missions, while the brunt of combat is borne by heavier vehicles.
The Trade Federation maintained its own standing military at a time when the galaxy was ostensibly at peace, citing the need to protect its valuable shipments.
On more than one occasion, Anakin Skywalker has forcibly commandeered a STAP by kicking its hapless droid pilot off and bringing the nimble vessel under his control.
When the Clone Wars erupted, many corporate armies joined the cause through treaties, defections, or lucrative partnership contracts. Trade Federation fighting forces formed the backbone of the Separatist military, though the organization cynically claimed neutrality in the conflict, as that was the most profitable stance.
STAPs often work in tandem with heavier vehicles such as the AAT battle tank, defending the flanks of the slower armored vehicles and skimming ahead as an advance patrol.