Gamma-rays and their future

The focus of this presentation is to go through some of the remarkable observations concerning gamma-ray cosmic accelerators and diffuse emissions. Additionally, I will cover the status of the new generation of gamma-ray ground-based observatories, CTA and LHAASO. To create this new generation of arrays, new technologies have been prepared concerning the photosensors and the optics. The recent start of multi-messenger astrophysical measurements indicates that there is a bright future to explore further the time domain of the universe with the current and in preparation instruments.