You probably know that iTunes can back up your iOS device when you sync it. You can choose to have your device backed up to iCloud or to your computer.
You can also manually back up your device; just click Back Up Now.
iTunes’ preferences shows you the backups available for your devices:
As you can see above, I’ve got two backups for my iPhone, Sugaree: one from this morning, at 8:55 am, and another from yesterday afternoon. iTunes saves one backup from each device – as you can see for the other devices listed in the window – but you can force it to “archive” a backup; when you do this, you’ll see the device name and the date and time of the archive, as in the last backup you see in the above screenshot.
To do this, right-click on a backup and choose Archive. iTunes quickly renames the backup, and saves it. You can do this as often as you wish, with the understand that these backups do take up a bit of space on your computer, depending on the type of content on your device. (My backups take up from 500 MB to about 1 GB, currently.)
If you have too many backups, you can delete some of them. Just right-click on a backup and choose Delete.
iTunes used to make these archived backups whenever you clicked Back Up Now; whenever you made a manual backup. Now you must choose to archive a backup yourself in the Devices preferences.
If you ever have serious problems on your iOS device, you can restore a backup, by connecting the device, and then clicking the Restore Backup button.