The term 'Retina display' is different from virtual retinal display. It is a trademark used by Apple, so you can only see Retina display on Apple products. The iPone 4, iPhone 4s, 4th generation iPod touch, 3rd generation iPad and 2012 Macbook Pro now all have retina displays.

Apple claims that retina displays have so high pixel density that the human eyes wouldn't be able to notice pixelation. It is said that the human retina can only process up to 300 pixels per inch (ppi) at a 10-inch distance from the eyes while iPhone 4 display has 326 pixels per inch. However, some experts claim that the resolution of the actual human retina is 447 ppi, which is much higher than the number claimed by Apple.