21.5-inch and 27-inch displays.

The new iMac has come a long way from the first 15-inch iMac. Take one look and you’ll see just how far. A 21.5-inch or 27-inch display with edge-to-edge glass covers nearly the entire front of the enclosure. When all you see is the display, nothing gets between you and what’s onscreen. Movies, TV shows, websites, photos — everything looks stunning on the new 16:9 widescreen iMac display.
LED backlighting.

When a display has more pixels, you need to push more light through them to achieve the best picture possible. LED backlighting in the new iMac does exactly that, with remarkable brightness and efficiency. Because the LED backlight doesn’t take up much space, the iMac enclosure stays thin — even with all the high-performance components inside