Google officially introduced Android M, the next version of its mobile operating system, at its annual I/O conference in San Francisco on Thursday.
As with 2014's Android L preview, which eventually became Android 5.0 Lollipop, Google hasn't yet granted Android M its delicious dessert name or a version number. Those details will likely come later this year when M makes its general debut on devices. For now, though, this is a developer-only affair.
Google Now gets smarter with Now on Tap
The least interesting thing about Google Now on Android M is that you can launch the Google Search app (where Google Now cards reside) by pressing and holding on the home key, instead of swiping up from the bottom of your device screen.

What will really elevate your heart rate is a much more context-sensitive Google Now that can understand the email you're reading , note the song you're playing and the dry cleaner you're using, and surface useful information about those very things. Google calls this feature Now on Tap.
Example: Showing the location of a gas station when you're driving back to the carrental lot before your flight (Google already knows all these things from the reservations you've made and the location of your phone.)
Example: Listening to a song and asking, "OK, Google, where's she from?" -- without having to name the artist.

Now on Tap also promises to alert you about times for the last train home, a cool event in your area or where you parked your car (an existing feature). If you go out, Google's Now on Tap will tell you when places are busy, and where you might want to go next.
Android Pay
Android M officially ushers in Android Pay, a mobile payments system that Google talked about during Mobile World Congress earlier in 2015. The Android Pay platform lets third-party apps process payments both within the app (think in-app payments) and in retail stores, using NFC. Google Wallet, the standalone mobile wallet app, won't disappear, but it will use Android Pay.

If your phone has a fingerprint reader, you can authorize payments with your print, as you can with iOS. (Samsung also has its own similar payment system, calledSamsung Pay.)
Android Pay will work with 700,000 stores, like Walgreens, Macy's and Best Buy, to give a few US examples.
Power!
Google's mobile devices are going to support the new USB Type-C standard of charging cable. That means it can be charged or also charge other devices. Better yet, it's got the same shape on both sides, meaning you won't have to grapple with which one is "up."

That's for charging up, but what about saving power to begin with? Android M also includes Doze, an energy-saving feature that Google says will use less power than the current standby mode. Basically, if you walk away from your device for a lengthy period of time, it hibernates to save your battery. You'll still hear important alarms and incoming messages, but with as little as half the power consumption of before.
App permissions
The update introduces a change to how apps use the resources on your phone or tablet, such as Wi-Fi connectivity, the camera and your photo library and contacts.
In the past, installing an app essentially waved the green flag for the whole bundle, requiring blanket approval of permissions. Now, apps will ask for access to parts of your phone or Google account when they need it. For instance, a messaging app might not ask for permission to use your camera until you try to take and send a photo. This is very similar to how iOS devices handle permissions -- apps ask for permission to use your camera, contacts or photos on a need-to-use basis.

Smoother linking transitions
Google has a new vision for smoothing out the way that Android links from an app to another app, and from the app to the Web. A lot of behind-the-scenes work will help developers create faster, more complete transitions when you skip around. This will roll out to users in Q3.
Developers only
Android M is available for developers, on Google's Nexus devices, where it'll incubate and grow until fall this year (we expect), when it should launch on Nexus devices in the wild before rolling out to other existing hardware.

When it does, M will pick up a version number, like Android 5.2 or 6.0, and a new sweets-themed name. That moniker is up in the air for now, but speculation ranges from Marshmallow to Muffin to Marzipan or even a branded name, like M&Ms (we saw this with Android 4.0 KitKat). Heck, we'll even throw Marmalade and Meringue into the mix.
Thanks for viewing this post.
Some of the information is from different websites.
Thanks Again.