Android 5.0 lollipop was a big upgrade from KitKat, and gave life to the new "Material Design."
This upgrade solved many security issues, and added new features to the settings. Some of them were the new settings in the notification menu. There are new bug fixes and other added features. Old viruses were solved, and new weaker viruses were found. However, there is a large issue: only a percentage of the world's Android phones were updated, leaving older phones behind and still vulnerable.