Aqua user interface

Mac OS X’s most recognisable feature, and most radical departure from Mac OS 9, was the Aqua interface, which contained soft, water-like elements. After the initial splash (sorry) at the launch of Mac OS X, Aqua got toned down and by 2014’s OS X Yosemite started a new trend towards a flatter ‘2D’ interface that went hand-in-hand with the latest iOS look and feel. Mac OS X launched with a splash, thanks to Aqua.