combat, but eventually evolved to aid in all aspects of flight - not just combat. HUDs were then standardized across commercial aviation as well, eventually creeping into the automotive industry. One of the first applications of HUD in automotive transport came with Pioneer's Heads-up system, which replaces the driver-side sun visor with a display that projects navigation instructions onto the road in front of the driver. Major manufacturers such as General Motors, Toyota, Audi, and BMW have since included some form of head-up display in certain models. Head-mounted display A head-mounted display (HMD), worn over the entire head or worn in front of the eyes, is a device that uses one or two optics to project an image directly in front of the user's eyes. Its applications range across medicine, entertainment, aviation, and engineering, providing a layer of visual immersion that traditional displays cannot achieve. Head-mounted displays are most popular with consumers in the entertainment market, with major tech companies developing HMDs to complement their existing products. However, these head-mounted displays are virtual reality displays and do not integrate the physical world. Popular augmented reality HMDs, however, are more favorable in enterprise environments. Microsoft's HoloLens is an augmented reality HMD that has applications in medicine, giving doctors more profound real-time insight, as well as engineering, overlaying important information on top of the physical world. Another notable augmented reality HMD has been developed by Magic Leap, a startup developing a similar product with applications in both the private sector and the consumer market. Mobile devices Mobile devices, including smartphones and tablets, have continued to increase in computing power and portability. Many modern mobile devices come equipped with toolkits for developing augmented reality applications. These applications allow developers to overlay computer graphics over videos of the physical world. The first augmented reality mobile game with widespread success was Pokémon GO, which released in 2016 and accumulated 800 million downloads. While entertainment applications utilizing AR have proven successful, productivity and utility apps have also begun integrating AR features. Google has released updates to their Google Maps application that includes AR navigation directions overlaid onto the streets in front of the user, as well as expanding their translate app to overlay translated text onto physical writing in over 20 foreign languages. Mobile devices are unique display technologies due to the fact that they are commonly equipped at all times. See also Extended reality Mixed