A review article for Contemporary Physics focused on Advanced LIGO, aimed at senior undergraduate students interested in GW/LIGO research and/or those new to the field and first making use of or contributing to aLIGO data. Gravitational-wave astronomy started in earnest in 2015 with the first observation of waves from a binary black hole merger by NSF’s LIGO detectors. Since that time, the signals from many compact objects have been observed with LIGO and Virgo, giving insights into the demographics of stellar black holes, the nature of neutron stars and the products of their coalescence. Detailed studies of the signals are in agreement with the predictions of General Relativity. The instruments which enabled these measurements are of extraordinary sensitivity, and the treatment of the data to enable the observational science requires a deep understanding of the instruments and best practices for analysis. The field is rich with future opportunities to participate in this broad swath of science.