4k

Apple will reportedly launch a 21.5-inch iMac with 4K display soon, with the company reportedly preparing for a release at some point next week.

4K video is a fancy name for 2160p, in other words twice the resolution of 1080p HD. That's a lot of pixels and it can take up a lot of storage space—300-400 MB of storage per minute of video—which is why Apple leaves it off by default on the iPhone 6s and iPhone 6s Plus. If you do want to shoot in 4K, however, either for the full resolution or just so you can pan, crop, zoom, or stabilize your 1080p, it's easy to turn on.

Apple is said to be preparing to launch a version of its 21.5-inch iMac with a 4K display. The desktop will reportedly launch by the end of October alongside OS X El Capitan.

You may not realize it, but the new Apple A8 processor on the latest iPhone 6 and iPhone 6 Plus can handle 4K video playback even though the smaller Apple phone has a native resolution of 1334 X 750 pixels while the larger Plus model has a 1080p Full HD display with 1920 X 1080 pixels. Though you won't get a pixel-for-pixel output on the phones' screens, the A8's ability to handle 4K playback means that users who sideload 4K content would be able to still watch it on their phones.