AstroSat has completed 5 years of successful in-orbit operation on 28 September 2020. AstroSat is ISRO's first Indian multi-wavelength satellite operating as a space Observatory. It is the only satellite which can simultaneously observe in the Far UV and a wide X-ray band from 0.3 to 80 keV using different instruments. This astronomy mission was conceived, following the success of several piggy back astronomy experiments flown earlier on Indian satellites. AstroSat is the result of collaboration between ISRO and several astronomy institutions within India and abroad. There are over 150 refereed publications resulting from data from AstroSat, in addition to Astronomy Telegrams, Circulars and Conference proceedings. This paper provides a brief summary of the evolution of the concept of Astrosat, how it was realized and scientific outcome from this mission.