A quasar is a type of extremely luminous and energetic astronomical object found at the center of some distant galaxies. Powered by supermassive black holes at their cores, quasars are among the most brilliant and powerful objects in the universe. As material falls into these black holes, it heats up and emits an immense amount of radiation, which can outshine the entire galaxy that hosts the quasar. Quasars are important to astronomers as they help in understanding the early universe and the formation of galaxies. They were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, during the 20th century.