Cadmium–Zinc–Telluride Imager (CZTI) onboard AstroSat has been a prolific Gamma-Ray Burst (GRB) monitor. While the 2-pixel Compton scattered events (100–300 keV) are used to extract sensitive spectroscopic information, the inclusion of the low-gain pixels ($\sim$20% of the detector plane) aftercareful calibration extends the energy range of Compton energy spectra to 600 keV. The new feature also allows single-pixel spectroscopy of the GRBs to the sub-MeV range which is otherwise limited to 150 keV. We also introduced a new noise rejection algorithm in the analysis (‘Compton noise’). These new additionsnot only enhances the spectroscopic sensitivity of CZTI, but the sub-MeV spectroscopy will also allow proper characterization of the GRBs not detected by Fermi. This article describes the methodology of single, Compton event and veto spectroscopy in 100–900 keV combined for the GRBs detected in the first year of operation. CZTI in last five years has detected $\sim$20 bright GRBs. The new methodologies, when applied on the spectral analysis for this large sample of GRBs, has the potential to improve the results significantly and help in better understanding the prompt emission mechanism.

Gamma-ray bursts are the most energetic transients occurring in the distant cosmos. They are produced by either the collapse of massive stars or the merger of compact objects like neutron stars or black holes. Currently, gamma-ray burst is the only astrophysical event successfully observed in different messengerssuch as gravitational and electromagnetic waves. Despite several decades of extensive observations and research, gamma-ray bursts still remain largely elusive in terms of their central engine, jet composition and radiation process. In this article, the author will review the recent observational and theoreticaladvancements made in the direction to resolve some of these enigmas and the future outlook.