Google has starting to roll out Android 6.0 Marshmallow to Nexus users. Of course, the newly announced Nexus 5X and 6P will ship with Android 6.0, straight from the factory. But Nexus 5, Nexus 6, Nexus 7 (2013), Nexus 9 and Nexus Player will get an over the air software update to Android 6.0 Marshmallow in the following days.

Android Marshmallow is the smartest Android version yet: Now on Tap serves up assistance when you need it, battery-smart features keep your device going longer, and new app permissions give you more control.

Now on Tap stays on task alongside you, pulling up relevant info. Say you receive an email about meeting a friend at the Central Park Zoo. Just tap and hold on the home button, and Now on Tap will assist you by providing links to information about the zoo, shortcuts to relevant apps and even suggest a calendar entry for the date, time and location.

Improving battery life is about building a bigger batterym, but also about improving the way your device uses the charge it has. With Android Marshmallow, Google has added two new features which decrease your device’s thirst for power.

With Doze, Android recognizes when your device is idle and automatically goes into a deep sleep state to conserve power. This saves up to 30% battery compared to Android Lollipop, according to Google.

The other new battery-conserving feature is called App Standby. This puts your seldom used apps into a reduced activity state to conserve battery for the apps you use more frequently.

Android Marshmallow also gives you the ability to customize and control which capabilities you give apps. With the new app permissions model, you pick and choose which permissions to grant apps at the time of use. Apps designed for Android Marshmallow only ask for a permission at the time it’s needed to use a feature. You can deny any permission and still continue to use the app. In addition,Google has added new settings for permissions that allow you to turn on and off any permission, for any app, at any time.

For fingerprint sensor enabled devices, Android Marshmallow gives you a new way to protect your device. On Marshmallow, your fingerprint is the gatekeeper to unlocking your device, authorizing transactions in the Google Play Store, signing into 3rd party apps, and zipping through checkout with Android Pay.

On Lollipop, Android made it easier to set up your new phone from your old one, migrating your apps and app data. With Android Marshmallow, you can breeze through setup on your Android TV or tablet too. Say "OK Google, set up my device" from your phone and you’ll quickly be up and running. For TV, Google will even transfer over your Wi-Fi passwords.