The Oculus Rift was the virtual reality headset first released to consumers by Oculus in 2016. The consumer model, commonly called the Oculus Rift CV1, began shipping in March 2016 after years of prototypes and developer kits.
The project began with Palmer Luckey's 2012 Kickstarter campaign, which helped revive mainstream interest in modern consumer virtual reality. Oculus distributed development kits, including the DK1 in 2013 and DK2 in 2014, so developers could create software before the retail headset arrived. Those kits were not the final consumer product, which is why the 2016 release is the important date in this question.
The Rift CV1 used two OLED displays, one for each eye, with a combined resolution of 2160 by 1200 pixels and a 90-hertz refresh rate. It connected to a gaming PC and used external sensors for positional tracking. Its launch price was $599.99, before later bundles included Oculus Touch motion controllers.
Google Cardboard was a low-cost smartphone viewer, while HTC Vive and PlayStation VR were competing consumer headsets released in 2016. The Oculus Rift was Oculus's own first mainstream retail headset.