Gamma Ray Bursts, the most powerful explosions in the Universe, represent a ket topic for different research fields in astrophysics. After nearly half a century since their discovery, some key aspects of the physics of GRBs are not clear yet. What makes them shine as bright bursts of gamma—rays? For several years, synchrotron emission faced major difficulties in explaining the observed spectral shape of GRBs, especially the X-ray spectrum being harder than what predicted by synchrotron emission. Recent observational developments seems to solve some of these difficulties but pose new challenges for their interpretation. Future observations may hold the key to unveil the nature of the prompt emission mechanism.
