Daydream is a discontinued virtual reality (VR) platform which was developed by Google, primarily for use with a headset into which a smartphone is inserted. It is available for select phones running the Android mobile operating system (versions "Nougat" 7.1 and later) that meet the platform's software and hardware requirements. Daydream was announced at the Google I/O developer conference in May 2016, and the first headset, the Daydream View, was released on November 10, 2016. To use the platform, users place their phone into the back of a headset, run Daydream-compatible mobile apps, and view content through the viewer's lenses.

Daydream was Google's second foray into VR following Cardboard, a low-cost platform intended to encourage interest in VR. Compared to Cardboard, which was built into compatible apps and offered limited features, Daydream was built into Android itself and included enhanced features, including support for controllers. Daydream was not widely adopted by consumers or developers, and in October 2019, Google announced that the Daydream View headset had been discontinued and that they would no longer certify new devices for Daydream.

At the Google I/O developer conference in May 2016, Google announced that a new virtual reality (VR) platform called "Daydream" would be built into the next release of their Android mobile operating system (OS)—Nougat (7.1). Daydream was Google's second foray into VR following Cardboard, which was a low-cost standard that utilized a cardboard viewer with plastic lenses that could hold a smartphone. Whereas Cardboard was used by running compatible apps and was accessible on most smartphones, Daydream was built into the Android OS itself and only worked on select phones that met the platform's standards, such as having specific hardware components. In January 2017, Google opened the Daydream program for all third-party developers.

Android Nougat introduced VR Mode, a low-latency, "sustained performance mode" to optimize the VR experience for Daydream. It dedicated a CPU core to the user interface thread to reduce visual issues that could induce nausea. Whereas the GPU normally sends frames to the device display in a "double buffering" mode on Android, VR Mode switched to "single buffering" to avoid intermediate frame buffer and instead draw frames directly to the display. The mode also allowed for asynchronous reprojection, whereby frames were slightly transformed to account for positional changes in the user's head that occurred during the 16 milliseconds that each frame was rendered and sent to the display. VR Mode also performance tuned the motion sensor pathways to result in quicker input from the device's accelerometer and gyroscope. The mode assisted developers in optimizing apps to a device's thermal profile. Overall, the performance improvements of VR Mode resulted in motion-to-photon latency decreasing on the Nexus 6P phone from 100 milliseconds on Android Marshmallow to less than 20 milliseconds on Android Nougat.

Daydream also included a new head tracking algorithm that combined the input from various device sensors, as well as integration of system notifications into the VR user interface.

Daydream allows users to interact with VR-enabled apps, including YouTube, Google Maps Street View, Google Play Movies & TV, and Google Photos in an immersive view. Google recruited media companies like Netflix and Ubisoft for entertainment apps.

The first-generation Google Daydream View was announced on October 4, 2016. Daydream-ready smartphones can be placed in the front compartment of the Daydream View and then viewed in VR through the headset's two lenses. The View distinguished itself from previous VR head mounts by being constructed out of a light-weight cloth material, as well as featuring capacitive nubs and an NFC chip to simplify the process of setting up virtual reality viewing. The Daydream View was released on November 10, 2016, initially in a "Slate" color option. Two new color choices, "Crimson" and "Snow", became available on December 8.

In a review of the Google Daydream View, Adi Robertson of The Verge wrote that the headset was the "best mobile headset" she'd ever used, complimenting its "squishy foam-and-fabric body" being "significantly smaller, lighter, and more portable than the Samsung Gear VR", and that its design "keeps the lenses relatively protected during travel". She also liked the device's weight distribution, writing that it "rests more weight on your forehead than your cheeks, an option I've found more comfortable" and that allows her to "wear it easily for hours at a time". She also praised the material, particularly its plastic sliders rather than velcro patches on the head strap, writing that it allows "a wider range of sizes and avoids gathering lint", and that the View's overall design "could almost pass for an airplane sleep mask", meaning that it "avoids looking ostentatiously high-tech or intimidating".