Step 1 Install iTunes and open it
Install iTunes 12 to your computer and launch it. Connect your iPhone to your PC with USB cable. Once your device being detected by the program, the information of your device can be read on the right side.
Step 2 Backup your iPhone
iTunes offers two paths for you to store your backups. You can make your choice by clicking the "iCloud" or "This computer" in the "Backups" box. And the backup begins with clicking the "Back Up Now" button.
In this case, a window will pop up to remind you to choose back up Apps or not. If you are willing to backing up apps that are not in your iTunes library, click the "Back Up Apps" icon, otherwise select "Don't Back Up Apps".
When it is done, go to "Edit" > "Preferences" > "Devices" to check the data backed up.
1. To speed up the backup process, the media files like songs and videos won't be backed up for their large sizes. But iTunes backs up the purchase history for them so you can get them back from the iTunes Store freely as long as you have bought before.
2. It is unable to view the backed up data on the computer directly.
It is easy to do iTunes backup, but after all, there is some limitations, say iTunes is incapable of backing up specific item on iPhone. Therefore, you might be interested in backing up your phone data with a third party tool, and here, I recommend iOS Transfer which enables you to do the iPhone backup in full package as well as specifically.