The Australian Open is the first of the four Grand Slam tennis tournaments to be held each year. It is held each January at Melbourne Park. The tournament was held for the first time in 1905. Like the other three Grand Slam events, it was contested by top-ranked amateur players and known as the Australian Championships until the advent of open era in 1968. Originally based at the grass courts at Kooyong in the city of Melbourne's inner south-east, the tournament was in danger of fading into irrelevance before being revived in 1988 with a shift to Melbourne Park (then called Flinders Park), a new (Rebound Ace) hardcourt venue next to the Melbourne Cricket Ground on the southern fringe of the central business district. Mats Wilander was the only player to win the tournament both on grass and on Rebound Ace.

Like all the Grand Slam tournaments, there are men's and women's singles competitions, men's, women's, and mixed doubles, as well as junior and master's competitions.

The Australian Open was held in December from 1977 through to 1985, returning to its original January date in 1987. In 1986, because of the return to January, no tournament was held.

The two main courts used in the tournament are Rod Laver Arena and Vodafone Arena and feature retractable roofs, which can be shut in case of rain or extreme heat. It is the only Grand Slam tournament that features indoor play. However, work has already commenced on a retractable roof for Wimbledon's Centre Court, which is expected to be completed by 2009.

Held in the middle of the Australian summer, the Australian Open is famous for its notoriously hot days. An extreme-heat policy is often put into play when temperatures (and humidity) reach dangerous levels.

The Australian Open typically has very high attendance, with the 2008 Australian Open achieving the highest ever day/night attendance record for any Grand Slam tournament of 62,885.

In 2008, the Rebound Ace surface, which had been in place for the past 20 years at Melbourne Park, was replaced by a cushioned acrylic surface known as Plexicushion. The main benefits of the new surface: better consistency and less retention of heat (due to a thinner top layer). This change was accompanied by changes in the surfaces of all lead-up tournaments to the Australian Open. Work began on the removal of the old surface on 4 June 2007. The decision has been met with much controversy, primarily due to the new surface's similarity to DecoTurf, the surface already being utilised by the US Open.

The most recent tournament was held in from 14 January through 27 January, 2008. The singles winners were Novak Đoković and Maria Sharapova.