- Music, video, apps, books, podcasts, audiobooks, ringtones, and iTunes U content you've purchased from Apple and downloaded to iTunes. This includes apps and media you've purchased on other iOS devices and downloaded to iTunes via automatic download.
- Music, video, books, and other media you've ripped or otherwise manually added to iTunes.
- Documents for individual iOS apps that use iTunes's File Sharing feature.
- Photos in iPhoto, in Aperture, or in folders on your Mac's drive that you've opted, in iTunes, to sync to your iOS device.
- Device backups (though only if you've opted for local backup instead of iCloud backup).
- Contacts, calendars, bookmarks, and notes (though only if you're syncing them locally, via iTunes's Info screen for your device, rather than via iCloud or MobileMe)
Once you've enabled Wi-Fi syncing in iTunes, Wi-Fi sync happens automatically, once per day, when your iOS device is connected to power and on the same Wi-Fi network as the computer running iTunes. (If you unplug from power after the sync starts, the sync continues.) You'll see a sync icon in the iOS device's status bar during any sync--you can continue to use the device during the sync. You can also force a Wi-Fi sync--with or without power--any time you're on the same Wi-Fi network as your computer and iTunes is running: On your iOS device, go to Settings > General > iTunes Wi-Fi Sync > Sync Now; or on your Mac, select your device in the iTunes sidebar and then click Sync in the lower right corner of the Summary screen.
Your iOS devices can also sync data wirelessly with iCloud, but iCloud syncing differs from Wi-Fi sync in significant ways. First and foremost, iCloud is the central storehouse of data, rather than your computer--once you've gotten your data into iCloud, your devices sync directly to it. In this way, iCloud is a lot like MobileMe syncing. But whereas MobileMe-to-iOS syncing handled only email accounts, contacts, calendars, bookmarks, and notes, iCloud also handles many of the same other types of data you can sync via iTunes. However, iCloud doesn't actually sync every type of supported data--for some items, it simply makes media available for you to download.
The types of data iCloud can sync with your iOS devices include:
- Contacts, bookmarks, calendars, and notes.
- Photos you've uploaded to iCloud--from your iOS devices, or iPhoto or Aperture on your Mac--using Photo Stream.
- Device backups--only if you've opted for iCloud backup instead of iTunes backup.
- Documents and data stored in iCloud by iCloud-enabled apps.
There are also types of data iCloud doesn't sync--it doesn't upload them to iCloud from your device--but does make available for automatic, over-the-air downloading to your device: