One reason for the tall, vertical tail on an airliner is to allow the pilot to compensate with the rudder for the yaw created when a wing-mounted engine fails.

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Meanwhile at Imperial College in London, Varnavas Serhides designed a plane that has no tail by taking advantage of advanced "fly-by-wire" controls and eliminating the need for a horizontal stabilizer and vertical tail, which also reduces drag.

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That tail is useful because it adds depth to the OS, in the form of a vertical row of "cards" which appear when you long-press the home button, and which grow intelligently based on what Google can glean about your life.

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