Android 4.4 KitKat is here and it comes preinstalled on the Nexus 5. Other Nexus- and Google Play-edition devices, , will also receive the update in the "coming weeks."
If you've already got your hands on the Nexus 5 or just want to get a head start on the latest Android OS, you might want check out Google's quick-start guide for Android. You can download the free guide from Google's Nexus support site, or from Google Play Books. The guide is broken down into six chapters and gives you a good overview of how to use the KitKat flavor of Android.
Once you've finished going over the guide, be sure to come back to CNET How To and check out the more advanced Android 4.4 tutorials, like .