An iPhone back up is definitely one of the most sacred things to most iPhone users. It contains all their contacts, messages, notes, photos and all sorts of other data that would was in their iPhone. This is required to restore all the data and information you need if you get a new phone, or lose yours or have to reinstall the software. It is important to know where the backup is stored and how to access it since sometimes iTunes may not be able to facilitate the entire back up. These back up folders can be used easily to access old stored pictures and files that may no longer be on your phone and give you full access to any and all information. iPhone back up is stored differently in Mac and Windows.
Documents and Settings\USERNAME\Application Data\Apple Computer\MobileSync\Backup\
Windows Vista/7/8/8.1 and 10
To access the backup location HOLD the Windows Key and Press R. In the run dialog, type the path as stated above depending on your operating system.
This will take you to the folder where your backups are saved.
On a Mac OS X
iTunes backups the iPhone/iPad backups to the following folder on a Mac OS X running iTunes.
To access it on a MAC, You can access Finder.
After you open Finder, choose Go -> Go to Folder. In the path where it asks for the folder location, copy/paste the following or browse manually to /Library/application\ support/mobilesync/backup.
This article only helps you locate, and view the backup locations. It would be best to restore via iTunes if you wish to restore your phone or ipad from a backup. This just ensures that the backup exists, the modification dates, etc.