Quasi-stellar radio sources, also known as quasars, are one of the most energetic and distant objects in the universe. These objects emit massive amounts of radiation, including radio waves, which can be detected by telescopes. While "quasi-stellar radio source" is the most commonly used term, there are several synonyms for these objects, including active galactic nuclei (AGNs), radio-loud AGNs, and radio-bright quasars. Additionally, some researchers refer to them simply as "radio sources" or "quasi-stellar objects." Understanding the properties and behavior of quasars is crucial for studying the evolution of galaxies and the universe as a whole.