The Australian Open is a tennis tournament held annually over the last fortnight of January in Melbourne, Australia. The tournament is the first of the four Grand Slam tennis events held each year, preceding the French Open, Wimbledon, and the US Open. 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 two types of hardcourt surfaces have been used at Melbourne Park – green coloured Rebound Ace up to 2007 and, afterwards, blue Plexicushion.
First held in 1905 as the Australasian championships, the Australian Open has grown to become the largest[clarification needed] annual sporting event in the Southern Hemisphere. Nicknamed "the happy slam" and often referred to as the "Grand Slam of Asia/Pacific" the tournament is the highest attended Grand Slam event, with more than 780,000 people attending the 2019 edition. It was also the first Grand Slam tournament to feature indoor play during wet weather or extreme heat with its eventually three primary courts, the Rod Laver Arena, Melbourne Arena and the refurbished Margaret Court Arena equipped with retractable roofs.