Instead of one complex, expensive robot, swarm robotics uses many simple ones that coordinate, inspired by how ants or bees achieve a lot together. The group can cover a large area, adapt if some units fail, and tackle tasks too big for a single machine.
Potential uses include searching wide areas, monitoring farmland and environments, and coordinated construction. The challenge is designing simple local rules that add up to useful group behaviour, and managing communication among many units, so much of the work remains in research, but the idea of resilient, scalable teams of robots is steadily advancing.