sentences:  It features men's and women's singles; men's, women's, and mixed doubles; junior's championships; and wheelchair, legends, and exhibition events.Prior to 1988 it was played on grass courts, but since then three types of hardcourt surfaces have been used at Melbourne Park – green coloured Rebound Ace up to 2007, blue Plexicushion from 2008 to 2019, and blue GreenSet since 2020.First held in 1905 as the Australasian championships, the Australian Open has grown to become one of the biggest sporting events in the Southern Hemisphere.