Retina Display, or later Retina HD Display on release of the iPhone 6 and the 6 Plus in September 2014, and Retina 5K Display on release of the October 2014 iMac (marketed and stylized by Apple with a lowercase ‘D’ as Retina display, Retina HD display, or Retina 5K display) are brand names used by Apple for screens that have a higher pixel density than their previous models. The terms are used for several Apple products, including the iPhone, iPod Touch, iPad, MacBook Pro, iPad Mini, iPad Air and iMac. Because the typical viewing distance is different, depending on each device’s use, the pixels per inch claimed to be of Retina quality can differ, depending on the size of the display, with higher PPI for smaller displays and lower PPI for larger displays. Later device versions have an even higher quality improvement, either counted by an increase in the PPI (the iPhone 6 Plus) and/or by an increase in the number of pixels (the iPhone 6 and 6 Plus, and iMac With Retina 5K Display), thus Apple using the moniker “Retina HD Display” or “Retina 5K Display”: 401 PPI: iPhone 6 Plus 326 PPI: iPhone 4 onwards iPod Touch (4th generation onwards) iPad Mini 2 onwards 302 PPI: Apple Watch 42 mm 290 PPI: Apple Watch 38 mm 264 PPI: iPad (3rd generation onwards) 227 PPI: 13-inch MacBook Pro (3rd generation) 220 PPI: 15-inch MacBook Pro (3rd generation) 218 PPI: iMac with Retina 5K Display 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. 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.