Android Marshmallow was initially announced at Google I/O on May 28, when it was released as the Android M developer preview. Several updates to the preview came out before Marshmallow was officially named on August 17. Google finally unveiled Android 6.0 Marshmallow, alongside the 2015 Nexus devices, on September 29, 2015.
As usual, Google's Nexus family was first to get the goods, and the brand new and were the launch devices for Android 6.0. Factory images for most of the existing Nexus range – the Nexus 5, Nexus 6, Nexus 9 and Nexus Player – appeared on October 5.
The Marshmallow lock screen is almost identical to Lollipop's, complete with expandable notifications and app shortcuts. But where Lollipop had shortcuts in the bottom corners that too you to the camera and dialer, Marshmallow replaces the dialer shortcut with one to Google’s voice search. This small update is the first clue as to just how integral voice commands are to Marshmallow.
The same voice command functionality appears on the home screen via Google’s dedicated search bar, complete with the colorful, post-Alphabet Google logo. The home screen itself is essentially the same as it was in Lollipop (the changes to Google’s search bar and app icons have rolled out to all devices via updates).
The app drawer in Marshmallow went through a couple of changes during the developer preview process and appears in the final version as a vertical scrolling list as opposed to the paginated horizontal list from Lollipop. You can scroll through the list or use a new scrubber bar on the right to jump to a particular letter of the alphabet.
As with Lollipop, Marshmallow has a two-part notifications/Quick Settings area. A single swipe down from the top of the home screen will pull down the notifications shade, where your expandable notifications live. A second swipe down on this screen, or a two-finger swipe down from the home screen, will take you to the Quick Settings panel.
The notifications area displays app notifications, which can be expanded or tapped to launch the full app. This area also shows persistent system notifications, such as when a Bluetooth device is connected or other system features are enabled. The 'dismiss all' button now faces the other direction compared to Lollipop, but it does the same thing.
The Quick Settings area displays your screen brightness slider as well as toggles for Wi-Fi, Bluetooth, mobile data and so on. As with Lollipop, these features can either be toggled on or off with a tap, or accessed further through a Quick Settings mini-menu or the relevant area of the full settings menu.
Doze is, after Google Now on Tap, perhaps the biggest thing in Marshmallow. Doze is an intelligent battery management feature that recognizes when your device is not is use, like when it has been lying on a bedside table for a while, and enters hibernation.