Rather than use flesh-and-blood warriors, the Separatists prefer mindlessly loyal soldiers that are unquestioning of orders, and easily controlled. The soulless ranks of their battle droid armies consists of tall, thin robotic soldiers with exposed joints and bone-white or rust brown metal finishes that gives them an eerie resemblance to animated skeletons. Battle droids are very efficient, and can be controlled from centralized command centers, like the enormous Droid Control Ships used by the Trade Federation. They are dim-witted, often suffering programming glitches that give them quirky personalities that are too slow to adapt to enemies like Jedi Knights and clone troopers.
General Grievous hardly hides his disdain for Separatist battle droids, who he is forced to command on his many missions throughout the Clone Wars. Often frustrated with the droids' insipid tactical sense and capabilities, many-a-battle-droid has found itself the unfortunate victim of Grievous' violent temper.
Poggle the Lesser controlled the vast droid factories found on his planet, overseeing production on a massive army of battle droids for the Techno Union to aide in the Separatist cause.
The Separatists had no standing military, but with the wealth of its member worlds were able to secure vast droid armies produced in foundries far from the Republic. The battle droid became the standard soldier of the Confederacy.
Geonosis was home to several droid foundries which manufacture the droid armies of the Separatist forces.
The principal enemy of the battle droid is the Republic clone trooper. Clones can think independently, creatively, and are far more versatile than their single-minded mechanical adversaries.