Retina Display

Retina Display (marketed by Apple with a lowercase 'D' as Retina display) is a brand name used by Apple for screens that have a higher pixel density than their previous models. Apple has applied to register the term "Retina" as a trademark in regard to computers and mobile devices with the United States Patent and Trademark Office, Canadian Intellectual Property Office, and in Jamaica. On November 27, 2012 the US Patent and Trademark office approved Apple's application and "Retina" is now a registered trademark for computer equipment.

When an Apple product has a Retina Display, each user interface widget is doubled in width and height to compensate for the smaller pixels. Apple calls this mode HiDPI mode. The goal of Retina Displays is to make the display of text and images extremely crisp, so pixels are not visible to the naked eye. This allows displays to rival the smooth curves and sharpness of printed text and immediacy of photographic prints.

These better quality displays have been gradually released over a number of years, and the term is now used for nearly all of Apple products containing a screen, including Apple Watch, iPhone, iPod Touch, iPad, MacBook, MacBook Pro, and iMac. Apple uses slightly different versions of the term for these models, including Retina HD Display for the iPhone 6 series, and Retina 4K/5K Display for iMac.

Apple's Retina Displays are not an absolute standard but vary depending on the size of the display on the device, and how close the user would typically be viewing the screen. Where users view the screen at a closer distance to their eyes, as on smaller devices with smaller displays, the displays have more PPI (Pixels Per Inch), while larger devices with larger displays where the user views the screen further away use fewer PPI. Later device versions have had additional improvement, either counted by an increase in the screen size (the iPhone 6 Plus) and/or by PPI (the iPhone 6 Plus, and iMac with Retina 4K/5K Display), thus Apple using the name "Retina HD Display" or "Retina 4K/5K Display".

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