In Star Wars: Episode I – The Phantom Menace, the Trade Federation army is formed by battle droids.
Battle droids are mass-produced infantry machines controlled through the Trade Federation’s droid control network. Their standardized bodies, limited independent judgment, and large numbers allow the Federation to field an army without relying on ordinary human soldiers.
The battle droids appear prominently during the invasion of Naboo and the Battle of Naboo. Their clumsy behavior provides comic moments, but the film also shows how overwhelming numbers and centralized control can create a serious military threat.
They are not the same as protocol droids such as C-3PO or astromech droids such as R2-D2. Those categories serve communication, translation, repair, or navigation roles. The later Star Wars prequel films introduce other battle-droid variants, including super battle droids and droidekas.