High energy particles, with their energies much higher than particle accelerators on Earth can reach, are constantly striking the Earth. These particles, so called cosmic rays, carry important information about their origin, acceleration, and propagation. TeV gamma-ray is a crucial window in order to answer this century-old puzzle of the origin of cosmic rays. Ground-based gamma-ray detectors, such as HAWC and LHAASO, are sensitive to gamma rays from sub-TeV to above 100 TeV and have a rich science case on both in and beyond our milky way Galaxy. The continuous time coverage and wide field of view also makes them critical in the era of multi-wavelength and multi-messenger astronomy. I will present recent highlights from the operational observatories and plans for future experiments.
