What does the iTunes backup of the iPhone include and what does it not include on Windows 10? I was under the impression that when I back up my iPhone with iTunes on Windows 10, everything is backed up, so that I can restore everything to a brand new iPhone.
iTunes iPhone backup size (6 GB)
However, when I look at the backup folder size at
C:\Users\&lt;username&gt;\Apple\MobileSync\Backup

it's only 6 GB.
Used storage on the iPhone (40 GB)
When I check the &quot;storage&quot; section on the phone, music alone is 9 GB, let alone another 14 GB of app data, photos etc.
Also, when I check iTunes, it shows &quot;Documents &amp; Data&quot; being around 25 GB.
Discrepancy (32 GB)
Therefore, I was wondering, what's missing in the iTunes backup?
My research so far
I've googled for https://www.google.com/search?q=what+does+itunes+backup+include
and found articles saying &quot;photos&quot; and &quot;music&quot;.
https://www.imobie.com/support/what-does-itunes-backup.htm
But that can't be true in my case. Or I'm missing something.
I've also not found any settings where I could configure what to include in the backup and what not. So I'd assume the entire iPhone would be backed up including the operating system and all the apps and all the data.
Versions

Windows 10, version 2004
iTunes version 12.11.0.26 (directly downloaded, not via the Windows app store)
straight from Apple themselves, as the first result on your Google search;

A computer backup of your device, which is not the same as a sync, includes almost all of your device's data and settings. A backup from a computer doesn't include:
Content from the iTunes and App Stores, or PDFs downloaded directly to Apple Books; Content synced from Finder or iTunes, like imported MP3s or CDs, videos, books, and photos; Data already stored in iCloud, like iCloud Photos, iMessages, and text (SMS) and multimedia (MMS) messages; Face ID or Touch ID settings; Apple Pay information and settings; Apple Mail data; Activity, Health, and Keychain data (to back up this content, you'll need to use Encrypted Backup in iTunes.)

your backup data should be located, by-the-by, at %appdata%\Apple Computer\MobileSync\Backup\.
the TL;DR is that a full iPhone backup will only actually back up data and settings important to the iPhone, such as keyboard layouts, dark/light mode settings, language preference, and more.
to back up your photos, music, contacts, and whatever &quot;other&quot; is classified as, you're looking for backing up with iCloud, which (unless manually disabled in Settings) is automatically done.