My research focuses on understanding the physics of stellar remnants and accretion processes in compact binaries through observations of X-ray binaries and their populations. My work  includes the discovery and characterisation of multi-wavelength counterparts to X-ray transients, reliable measurements of compact object masses, and the development of surveys aimed at increasing the number of binaries suitable for dynamical studies. The measured masses are used to infer the formation mechanisms of compact objects, to understand the physics of the electromagnetic spectrum emitted by accreting and ejected matter, and to help explain the origin of gravitational-wave progenitors.