Probes are robotic drones and stand at at the forefront of protoss colonization and military efforts. They were originally designed by the Khalai Caste to lay the foundation for protoss colonies on hostile worlds where living workers would be at too great a risk. Probes are functional, light, and easy to produce. Their outer shell does not offer much in the way of protection but it allows probes to operate virtually anywhere without sacrificing speed or mobility. The frame can also absorb light and turn it into energy, forgoing the need for a power supply.
The probe truly shines in its service to protoss military might, providing service to the nexus of any protoss base. They are also used to warp in structures, manufacturing and planting micro-beacons, allowing fully functional buildings to be warped in over interstellar distances. This process enables the protoss to quickly settle on new worlds, or establish nexus points to strike at their enemies, while only using a handful of probes.
As multipurpose platforms designed to operate in hazardous environments, probes are equipped with a miniature energy projector, which shoots out a particle beam. Commonly used to collect samples and mineral crystals, the beam can be boosted to cause kinetic damage to targets deemed a threat. Probes are also often used as rudimentary spies, sent ahead to survey the potential locations of enemy encampments. [Source: wikia]