iCloud allows iOS device users to store contents within our devices such as notes, address book, calendar, photos, musics, Safari bookmarks to Apple server. But unfortunately we still can not sync video yet using this service, at least when I write this post. May be in the future Apple will add that video synchronize ability in iCloud. Just wait.
And yes, iCloud can be used to backup your contents. You are able to drag and drop any contents you want to the available iCloud driver folder, so you can manage your files from different places.
One more thing, developers of the apps can now integrate iCloud drive into their apps so if we install the app then we can save them to iCloud Drive.
Changes and interpolations you do to your iPhone can be done in iCloud. This service requires you to have an Apple ID, and can be activated on Mac OS X 10.7 or iOS 5 or newer.
If you don't have an Apple ID, you can create Apple ID directly from your iPhone now.
And it's suggest that anyone who have iOS 8 installed should not enable iCloud Drive yet, as that cloud service relies Mac OS X Yosemite to work. And there is a syncing issues between Mac OS X and iOS right now. Thus you better set it disabled now, wait until latest Mac OS version is released in October this year.
- Free email address, like this "email@example.com".
- Find my iPhone, to make us able to use geo-location, lock and then erase content within our iPhone, Mac, iPod Touch or iPad if we loose them or being stolen.
- Photo Stream, a service that will automatically upload and save photo in your device's camera to be accessed by other device.
- Device backups, iPhone or iPad content can be backup automatically and routinely with a service namely iCloud mobile when your device is locked and connected to Wi-Fi network. You can also perform a manual backup too.
- Downloads, you can access iTunes store, App store, iBookstore to buy or purchase stuffs and be saved in digital locker.
Update Feburary 2015! Here is a new list of iCloud storage plan price.
- 5 GB (Free)
- 20 GB cost 99¢ per month.
- 200 GB cost $3.99 per month.
- 500 GB cost $9.99 per month.
- 1 TB cost $19.99 per month.
Additional information fix error 1015 in iTunes.
Since you have fully understood what is iCloud. Now you can go ahead to create a free iCloud email address and use it to do several things like login to iTunes, use the service and sync / backup your device contents.