Android Oreo is the 8th major release of the Android operating system. It was first released as a developer preview on March 21, 2017, with factory images for current Nexus and Pixel devices. The final developer preview was released on July 24, 2017, with the stable version released in
August 2017 .
For more
information Visit https://en.wikipedia.org/wiki/Android_version_history Thanks
Amatya