A quasar is an exceptionally luminous active galactic nucleus, representing one of the most energetic phenomena in the observable universe. These sources are powered by supermassive black holes that reside at the centers of galaxies and are actively accreting matter. The intense gravitational energy released as matter spirals into the black hole generates powerful jets of radiation that can extend far beyond the host galaxy. The immense brightness and vast distances involved make quasars appear point-like in early astronomical observations, hence the name "quasi-stellar." Observing quasars helps astronomers study the early evolution of galaxies and the physical processes governing the most massive objects in the cosmos.