Recent progress in high-energy astrophysics, driven by modern X-ray timing and spectroscopy from missions such as NICER, NuSTAR, and AstroSat, has expanded our understanding of the most energetic and rapidly evolving phenomena in the Universe. In this talk, I will present crucial findings on accreting compact objects across the mass spectrum, including neutron stars, black-hole X-ray binaries, and rare transients. These studies demonstrate how universal physical processes govern accretion flows, magnetic activity, and high-energy radiation. Particular emphasis will be placed on thermonuclear X-ray bursts — brief and powerful explosions from unstable hydrogen and helium burning on neutron-star surfaces in accreting binaries. These events probe nuclear burning, trace nucleosynthesis pathways, and constrain the neutron-star equation of state, a key open question in modern astrophysics. 

I will also highlight coordinated multiwavelength campaigns that link X-ray variability with optical and radio signatures, offering new insights into accretion dynamics and binary evolution. Finally, I will provide an update on the long-term calibration of the JEM-X instruments onboard ESA's INTEGRAL mission and the development of the INTEGRAL Legacy Archive, delivering enduring resources for the high-energy astrophysics community.