It's been a few days since Google's new mobile operating system, the Android M Developer Preview, has been introduced at the company's I/O 2015 keynote. A number of brand new features of the OS have been unveiled, but a few stood out among the rest.

We highlighted the top five features of the Android M below.

RRO Theme Engine

The RRO Theme Engine, which was first contributed to AOSP by Sony in 2014, aims to provide new changes in Android's functions, XDA reported. RRO, or Runtime Resource Overlay, allows users "to replace resources in a running application without making changes to the app's source code."

Basically, an app's appearance can be changed without modifying the app itself. The app will not become aware of any configurations placed upon it and will continue working on its expected function, XDA added.

For how the RRO functions, head over to Sony's Developer Blog.

Tap Now

Tap Now is also one of the most notable features of Android M. According to Android Origin, this feature is capable of scanning a user's smartphone screen for any references to maps, events, names, flights, and albums, among others.

"For instance, if a friend texts you a message about an artist, you can hold your home button and Google will scan that screen, find the artist's name and give you some instant information about them," Android Origin wrote.

The upside to this is it will allow users to minimize typing information on their mobile devices all the time. Instead, Tap Now will deliver information to the user's own screen.

Contact Merging

Android Police wrote that Android M also has an updated contacts app in store for its customers. The app will allow users to select multiple contacts from the main listings to be merged, deleted, or shared all at once. Some would assume that this feature already existed in previous apps, but apparently, it has not yet been rolled out.

With this feature in Android M, users can long-press any selected contact, then use the checkboxes that appear on the screen to choose and modify other contacts, Android Police added. Of course, a confirmation will pop out before changes will be applied.

Doze

Android M also has a new feature called Doze, an app responsible for motion detection capable of better management of the handset's power. If your device was unused for a specific period of time, apps are put into sleep mode to conserve battery power. However, alarms and high-priority messages and notifications will still continue to function, Paste Magazine reported.

Fingerprint Support

Devices with fingerprint scanners can now use the feature for authentication instead of a password or a pin number, Paste Magazine wrote. This Android M function will give users faster payment transactions using Android Pay.

The sensor is also capable of giving users access to sensitive data in their smartphones using just their fingerprints, BGR reported.

Google didn't mention a specific launch period of the Android M. Android Geeks, however, speculated that the OS will be released in October 2015 along with a new Nexus device.