So it backs up the data as well? Or just the apps? I'm still grasping the iOS back up thing.
What iCloud backs up
iCloud automatically backs up the information on your devices?iPhone, iPad, and iPod touch?over Wi-Fi every day when they are turned on, locked, and connected to a power source. When your iOS device information is backed up in iCloud, you can easily set up a new device or restore information on one you already have.
Here?s what iCloud backs up:
Purchase history for music, movies, TV shows, apps, and books
Your iCloud backup includes information about the content you purchased, but not the purchased content itself. When you restore from an iCloud backup, your purchased content is automatically downloaded from the iTunes Store, App Store, or iBooks Store. Some types of content aren?t downloaded automatically in all countries, and previous purchases may be unavailable if they have been refunded or are no longer available in the store. For more information, see the Apple Support article Availability of iTunes redownloads. Some types of content aren?t available in all countries. For more information, see the Apple Support article What can I buy from the iTunes Store in my country?.
Photos and videos on your iOS devices
However, if you turn on iCloud Photo Library on your iOS device (iOS 8.1 or later) or Mac (OS X v10.10.3 or later), your photos and videos are already stored in iCloud, so they aren?t included in your iCloud backup.
Device settings
App data
Home screen and app organization
iMessage, text (SMS), and MMS messages (requires the SIM card that was in use during backup)
Ringtones
Visual Voicemail password (requires the SIM card that was in use during backup)
Health data
HomeKit configuration
Apple Watch content is backed up automatically to your paired iPhone. For more information, see the Apple Support article Back up your Apple Watch.
Your iOS device backup only includes data and settings stored on your device. It doesn?t include data already stored in iCloud. That includes contacts, calendars, bookmarks, mail messages, notes, shared photo albums, iCloud Photo Library, My Photo Stream, and documents you store in iCloud Drive. If your iOS device isn?t set up for iCloud Drive, but is set up for iCloud Documents & Data, your documents stored in iCloud are backed up.
Source:
https://support.apple.com/kb/PH12519?viewlocale=en_US&locale=en_US