The detections of gravitational waves from the collisions of stellar-mass black holes by the LIGO Scientific & Virgo Collaboration have opened a new window onto the Universe. Even though multiple formation mechanisms have been theorized in the literature, the question regarding their origin remains open. The first part of this thesis aims to study merging binary black holes (BBHs) formed from isolated binary evolution in galactic fields. In particular, we model the distribution of their observational properties such as black hole masses, spins, and their merger redshifts. In the second part, we consider model predictions for alternative formation channels, and illustrate how one could leverage these signatures to interpret and quantify the origin of the detected sample of BBHs. In the last part, we discuss the implications on the observable population of electromagnetic transient events of our stellar binary models, which could potentially be used to constrain further the formation mechanisms of merging BBHs.