Caroline Wozniacki won her first Grand Slam title at the Australian Open by defeating Simona Halep in the final and returned to the WTA no. 1 singles ranking for the first time since 2012. Halep then went on to win her first major at the French Open on her fourth appearance at a Grand Slam final, defeating Sloane Stephens in three sets. Angelique Kerber won her third Grand Slam singles title at Wimbledon, defeating Serena Williams in the final and becoming the first German since Steffi Graf in 1996 to lift the trophy. Naomi Osaka won her first Grand Slam title, defeating Serena Williams in the final. At the age of 20, Osaka became the first Japanese woman to win a Grand Slam singles title and the youngest US Open champion since Maria Sharapova in 2006.
The 2018 WTA Tour calendar comprises the Grand Slam tournaments, supervised by the International Tennis Federation (ITF); the WTA Premier tournaments (Premier Mandatory, Premier 5, and regular Premier); the WTA International tournaments; the Fed Cup (organized by the ITF) and the year-end championships (the WTA Tour Championships and the WTA Elite Trophy). Also included in the 2018 calendar is the Hopman Cup, which is organized by the ITF and does not distribute ranking points.