Android 5.0–5.1.1 "Lollipop" is a version of the Android mobile operating system developed by Google, spanning versions between 5.0 and 5.1.1. Unveiled on June 25, 2014 at the Google I/O 2014 conference, it became available through official over-the-air (OTA) updates on November 12, 2014, for select devices that run distributions of Android serviced by Google. Its source code was made available on November 3, 2014.
One of the most prominent changes in the Lollipop release is a redesigned user interface built around a design language known as Material Design, which was made to retain a paper-like feel to the interface. Other changes include improvements to the notifications, which can be accessed from the lockscreen and displayed within applications as top-of-the-screen banners. Google also made internal changes to the platform, with the Android Runtime (ART) officially replacing Dalvik for improved application performance, and with changes intended to improve and optimize battery usage.
As of September 2016, statistics issued by Google indicate that 35% of all Android devices accessing Google Play run Lollipop