Android releases updates to its operating system on a regular basis to enhance functions, fix bugs and introduce new features. The specific process of updating your device varies by which device you own, but all use a similar approach. Once you've received notification that an upgrade is waiting for your device, back your system up to prevent any data loss due to the upgrade. And ensure your device's battery is fully charged, as these types of updates take time to complete and should not be interrupted.
When installing an over-the-air update, connect to a Wi-Fi network when possible. Operating system updates are data-intensive and will install faster over Wi-Fi. Connect your phone to a wall charger during the update process.
Some Android updates may wipe the data off your device. Before installing an update, be sure to sync your phone with the Gmail account associated with it. Apps that have been purchased through the Android market are available for download even after a data wipe. You do not have to purchase them again.