Absolute Magnitude

The apparent magnitude that a star would possess it if were placed at a distance of 10 parsecs from Earth. In this way, absolute magnitude provides a direct comparison of the brightness of stars. The apparent magnitude of a star is based upon its luminosity and its distance. If all stars were placed at the same distance then their apparent magnitudes would only be dependent on their luminosities. Thus, absolute magnitudes are true indicators of the amount of light each star emits.
Our Sun's absolute magnitude is +4.9. The most luminous star, known as S Doradus, has an absolute magnitude of about -8.9. The faintest dwarf stars have a magnitude of about +21.