Abstract: X-ray binaries, the most luminous objects, harbor the universe's fascinating objects: neutron stars and black holes that accrete from a binary companion star. Fast X-ray timing and spectral observations are excellent diagnostic tools that enable us to probe regions of strong gravity, dense matter, and strong magnetic fields and explore stationary space-time metrics inaccessible to gravitational-wave detectors. In this talk, I will discuss discoveries of coherent and incoherent signals in the light curves from high-time resolution observatories. Presenting results from the AstroSat survey, I will discuss the discovery of an intermittent accretion-powered millisecond X-ray pulsar (AMXP), a significant addition to a small set of 25 known AMXPs, and potential gravitational wave sources. Shifting the focus to the power of the multiwavelength probe of accreting systems, I will present findings from dense multi-wavelength campaigns on the neutron star and black hole systems and build on these discoveries to create a comprehensive picture that can be used to understand systems seen at different mass accretion rates. Finally, I will conclude by emphasizing the potential of X-ray polarization measurements combined with X-ray timing-spectral and multi-band observations.