Advanced LIGO-Virgo have detected tens of stellar mass compact binary mergers, including binary black holes, binary neutron stars, and potentially neutron star-black hole mergers. In this talk I will focus on a few topics we can learn from these binary mergers: the electromagnetic counterparts of gravitational-wave events, the nuclear equation-of-state, and cosmology. I will first summarize the current status and discuss the future projections. I will then present a few ideas to expand and improve the study on these topics.