The term very-high-energy gamma rays (VHEGR) is used for gamma rays in the 100GeV to 100TeV range of energy-per-photon. Such high-energy photons are detected, typically with detectors for this specific range that detect Cherenkov radiation resulting from interaction of the high-energy photon with the Earth's atmosphere (Cherenkov detectors). The gamma rays are of interest because they are assumed to travel very straight, increasing the chances of identifying the source.
The term VHE is also used more generally for this energy range.
Beyond 100TeV is ultra-high-energy gamma rays.