Abstract: In 2017 the sensational gravitational wave event GW170817 was confirmed to originate from a binary neutron star merger. This was the first time in human history that such a violent catastrophic phenomenon was detected. A binary neutron star system consists of two co-rotating neutron stars, which may form after a very long time during the evolution of normal binary stars. We present a comprehensive introduction to this merger event, including a few aspects before and after the merger. In the near future, after an upgrade of current observational instruments, we may expect to detect further similar gravitational wave events and their various electromagnetic counterparts.