Everywhere you look in OS X, you’ll find visual effects that would make any other operating system think about early retirement.
For example: Menus are transparent, and when you release them, they fade away instead of snapping off. You can set Excel 3-D graphs to be slightly transparent so that they don’t block other bars in a 3-D graph. When you paste files into windows in icon view, their icons fade into view. When you open an especially long message in Mail, its text fades in from white. When you use Launchpad, it fades in and out. And when you switch accounts using Fast User Switching, your work environment slides off the screen as though it’s pasted on the side of an animated cube.
All these visual goodies owe their existence to Quartz (or its enhanced successor, Quartz Extreme, which is not available on older Macs).
OS X understands dozens of Mac and Windows graphics file formats. Better yet, its Preview program can open such graphics and then export them in a different format, making it an excellent file-conversion program.