Apple's new iOS 7 operating system implements something called "parallax."
This design feature allows you to "see through" the the drop-down notifications menu and glimpse the apps underneath.
Simply put, parallax in iOS 7 is what Apple is calling a group of layered planes that create a feeling of depth.
But Instapaper founder Marco Arment points out that Apple is really using a virtual version of the first parallax camera, invented by Walt Disney animator Ub Iwerks, back in 1933.
The animator's camera rig was used to create a 3D effect by using four glass planes stacked on top of each other, with a camera mounted above.
These multiple layers are virtually simulated by Apple, which marks Apple's move from a single-planed operating system to the depth-heavy multiplane in iOS 7.
You can check out what the original parallax camera looks like here.
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