The PeVatrons and the HAWC Observatory in Mexico

The discovery of ultra-high energy gamma-ray sources (detected at energies $\geq$ 100 TeV) thanks to highly sensitive observatories such as the High Altitude Water Cherenkov (HAWC) Observatory, the Tibet AS-gamma Experiment, and the Large High Altitude Air Shower Observatory (LHAASO), marked the beginning of the sub--PeV and PeV era in gamma-ray astrophysics (energies $\sim$ 0.1 to 100 PeV). This new astrophysics is closely related to the emerging topic of PeVatrons, in which HAWC has played a remarkable role and will continue to contribute discoveries and relevant studies thanks to the better data provided by the installed outriggers. In this paper, we present a brief overview of the PeVatrons and the HAWC observatory.