Present Iranian National Flag is designed and adopted after the Islamic Revolution of 1979. It's emblem represents the name of Allah. The words of "Allah-O-Akbar" (God is Great) are also shown on the center-border of green and red color.
Former Iranian National Flag is the best-known symbol of Iran in recent centuries, however, has been the lion and sun motif, which is probably a graphic expression of the astrological configuration of the sun in the sign of Leo, although both celestial and animal figures independently have a long history in Iranian heraldry. The lion and sun emblem is very ancient, and Ferdowsi our epic poet writes that it was used by Rostam, the legendary national hero. Late in the nineteenth century an earlier scimitar motif was combined with the lion and sun and superimposed on a tricolour of green, white and red, and, with minor modifications, this remained the official flag until the revolution of 1979.