It is recommended to install the latest available updates to keep your i Phone secure and get access to the latest features.You can download and install updates directly from your device, or you can use i Tunes. Your i Phone or i Pad will continue to download the update and will send you a notification when the update is ready.
Before you start the download, connect your device to a power source so that the battery doesn’t drain during the update process.
It can take anywhere from a few mins to an hour for the update to download and install, depending on how Apple’s servers are handling the load and your internet connection.
If you have jailbroken your i OS device and cannot live without your favorite jailbreak apps and tweaks then it is recommended that you avoid updating to i OS 9.3, until Pangu or the Tai G team release a tool to jailbreak i OS 9.3.
One of the golden rules of jailbreaking is to stay where you are to improve your chances of jailbreaking your i OS device.
i Phone i OS update means, to update the current operating system version of your i Phone.