OS X Mountain Lion: Store your content in iCloud
iCloud stores your content and wirelessly pushes it to your Mac, iOS devices, and PC. iCloud is built into your Mac apps, so they stay up to date with the apps on your other devices set up with iCloud and with the web apps on the iCloud website. Thereʼs no need to dock your iOS device or sync it to your computer.
For information about system requirements for devices that can use iCloud, see this Apple Support article:
Mail, Calendar, Contacts, Reminders, and Notes
Make changes with the Mail, Calendar, Contacts, Reminders, or Notes apps on your Mac, and those changes appear automatically on your other devices. Likewise, changes you make on other devices appear automatically in your Mac apps. You can also access your mail, contacts, calendars, and reminders on the iCloud website.
On your Mac, you set up Mail, Calendar, Contacts, Reminders, and Notes by turning on iCloud services in System Preferences.
Use Mail with your iCloud account
Manage your entire schedule
Share iCloud calendars
Manage your contacts
Add items to reminders lists
Set up Notes for your accounts
Safari bookmarks and tabs
iCloud keeps your bookmarks and Reading List the same in Safari on your Mac, iPhone, iPad, and iPod touch. On your Mac, Safari also uses iCloud to let you open tabs that are open on your other devices. You set up the Safari service in iCloud preferences.
See webpages from your other devices with iCloud Tabs
Documents in the Cloud
When you use apps that work with the Documents & Data service, iCloud can store your documents. After you save or move documents to iCloud, you can access your documents in iCloud by using the same apps on other devices set up to use the Documents & Data service. You don’t have to remember to save your changes or remember where you saved your documents. iCloud automatically keeps your documents up to date on all your devices.
With your documents stored in iCloud, they’re ready whenever you need them. You can access your documents in iCloud—with your latest updates—whichever device you’re using.
To see how it works, turn on the Documents & Data service in iCloud preferences, and then use Preview and TextEdit to access your documents in iCloud. You can use those apps to save new documents directly in iCloud, open existing documents directly from iCloud, and move documents from your Mac to iCloud. Do this on more than one Mac with OS X Mountain Lion, and you can access your Preview and TextEdit documents in iCloud, no matter which Mac you use.
iTunes in the Cloud
Music you purchase in iTunes appears automatically on all your devices that are set up with iCloud. You can also download your past music or TV show purchases.
After setting up Photo Stream, photos you take on your iPhone, iPad, or iPod touch appear automatically in iPhoto or Aperture on your Mac. iPhoto and Aperture are available from the Mac App Store.
Back to My Mac and Find My Mac
You can use the Back to My Mac service to view and control the screens of your other Mac computers over the Internet.
If you turn on the Find My Mac service in iCloud preferences and you lose your Mac, you can locate it from the iCloud website. You can also remotely lock or wipe it.