Very high energy (VHE, > 100 GeV) gamma-ray emission from Gamma Ray Bursts (GRBs) has long been predicted but was first detected in recent years by the ground-based air-Cherenkov telescopes H.E.S.S. and MAGIC. While the sample of GRBs detected in VHE gamma-rays is still very small, it is already posing interesting questions and challenges to theoretical models, especially after detection of GRB 221009A, the brightest GRB ever detected, by the Large High Altitude Air Shower Observatory (LHAASO) with gamma-ray energy exceeding 10 TeV. Detection of VHE emission from GRBs has
implications for the particle acceleration and emission mechanism, properties of the jet and environment surrounding the GRB, intergalactic media, as well as for fundamental physics. In this talk we will focus on these topics, progress made to date towards understanding them and what remain to be done.
