Quasars, or quasi-stellar objects, are extremely bright and distant celestial objects powered by supermassive black holes at the centers of galaxies. As matter falls into these black holes, it heats up and emits vast amounts of energy, making quasars some of the most luminous objects in the universe. They can outshine entire galaxies and are often used to study the early universe. Discovered in the 1960s, quasars are typically found billions of light-years away, meaning we see them as they were in the past. Their light can provide valuable information about the formation and evolution of galaxies, as well as the expansion of the universe.