If you own an Apple mobile devices, you have to back it up, because Apple gives you two simple and free ways for storing a copy of your information: iTunes and iCloud.
The benefit of backing up using an iCloud is that it's automated and can happen wirelessly. The downside is Apple only gives you 5GB space for free, so if you need more, you have to pay for it.
With iTunes, there's no space limitations. It creates backups of your iPhone, iPad, or iPod touch right on your computer. Therefore, the amount of space allotted to your backups is in your control. If you back up using iTunes, you can do it by connecting your iO device to your computer or by turning on wireless syncing with iTunes over Wi-Fi. Here's how it's done.
Before you make a backup of your iPhone or iPad using iTunes, it's a good idea to check whether you have the latest latest version of iTunes (go to Help > Check for Updates), but it's often not necessary.
Make sure iCloud is turned off. On your iPhone, go to Settings > [Your Name] > iCloud > iCloud Backup and toggle iCloud Backup to off. Then go to Settings > General > iTunes Wi-Fi Sync, which will prompt you to connect your iPhone to your PC. Sign in to iTunes using your Apple ID, and look for the small iPhone icon. See below.
In the menu that appears on the left, select Summary and scroll down to Options. Select "Sync with this iPhone over Wi-Fi" and click Apply on the bottom right. See image below.
Disconnect your iPhone from the PC; if your PC and iPhone are on the same Wi-Fi network, your phone should appear in iTunes and allow for wireless backups.
With a Cable
Connect your iPhone or iPad to your computer and launch iTunes. Your phone will appear as a small icon up top.
Click that phone icon, and in the left-hand menu under Summary, click the items you want to back up. If it's music, for example, click Music and check the box next to Sync Music. Choose whether you want to back up your entire library or select tracks and albums. Click Apply and do the same for movies, TV shows, and whatever else you want to sync.