People that don't backup their iPhone / iPad always scare me. Why ? Because those that don't say they have nothing on there that they can't get back - FALSE! There is ALWAYS something on your phone that you need, be it contacts, notes, pictures - an array of different things.
Please everyone - even if you think you don't - YOU DO !!!!
Apple's iCloud servers will automatically backup your iOS device, assuming that iCloud Backup is enabled. To enable iCloud navigate to Settings -> iCloud -> Backup & Storage.
The backup runs automatically every day when your device is:
Connected to the Internet via Wi-Fi
Connected to your charger
Your device screen is locked
You can backup with iCloud manually if you are connected to a Wi-Fi network by selecting - Settings -> iCloud -> Storage & Backup -> Back Up Now. This should be done PRIOR to each and every update.
If you don't use iCloud, make sure you have connected your iPhone/iPad to your computer to backup with iTunes.
Backing up your data is essential to insure against damage or loss to your iPhone. The process will also make it possible to easily transfer data from your device to a new iPhone should you chose to upgrade.
To write a current backup to your computer:
Connect the iPhone to the computer with a USB cable
Click on your iPhone under DEVICES in the left menu
Make sure the Summary tab at the top of iTunes is selected
Under the Backup section, check the "Back up to this computer" radio button
Click the Sync button