Quasar selection is a research area within astronomy that focuses on identifying and categorizing quasars, which are extremely luminous and energetic objects located in the centers of galaxies. Quasars are powered by supermassive black holes and emit intense radiation across the electromagnetic spectrum. Researchers use various techniques to select and study quasars, including identifying their unique spectral features, analyzing their variability in brightness, and using advanced data mining algorithms to detect them in large surveys. Quasar selection plays a critical role in understanding the evolution of galaxies, the growth of black holes, and the overall structure of the universe.