Astrophysical black holes are possibly the most interesting objects in the universe. In physics, black holes are one of the best laboratories to test general relativity in the strong gravity regime. In astrophysics, the smaller black holes are the endpoints of stellar evolution, providing the unique opportunity to study the gravitational collapse of matter into a single point laying beyond the light-trapping, one-way membrane known as the horizon. Meanwhile, supermassive black holes in active galactic nuclei (AGN) are believed to be chief agents in determining the structure of the universe via feedback to their host galaxies. Until the detection of gravitational waves by LIGO/Virgo, the most effective way to detect and study black holes has been through their interactions with surrounding matter, particularly by observing their energetic emissions in the X-ray band. In this talk I will describe some of the spectral and timing techniques currently used for the study of accreting compact sources, with emphasis in the modeling of the reprocessed X-ray spectrum in accretion disks around black holes. I will describe how these models are being implemented to reproduce a plethora of observational data, in order to derive fundamental physical quantities for these systems.