Apple first used the word "retina display" to describe technology in June 2010. It speaks of a monitor with a sharpness of more than 300 dpi. The iPhone 4, which was also unveiled in June 2010, is the first Apple device to feature a retina display and has a screen density of 326 pixels.

Retina displays are so-called because of how the high-resolution monitor looks to the human eye. When looking at a monitor from a distance of about 12 inches, most people cannot distinguish individual pixels when the density is greater than 300 dpi. As a result, the pixels appear to blend together, giving the image a seamless appearance. This is comparable to high-sampling-rate digital audio recordings. We hear the music as a seamless analog transmission because the audio clips are so near together.

There is no statistically verified figure that precisely describes a retina display because different individuals have superior eyesight than others. In reality, some individuals might actually be able to recognize specific images on a retina monitor. However, a retina display will appear significantly crisper to all viewers than a standard computer monitor, which has a density of 72 dpi.

When using a device with a tiny screen, like an iPhone or iPod Touch, Retina screens are particularly helpful for viewing writing. Medium-sized text is simpler to read and tiny text is more readable due to the higher density. Retina screens are anticipated to be made accessible in bigger devices, like the iPad and HiDPI computers, as display technology continues to advance.