Steve Jobs introduced the iCloud service at the Apple World Wide Developers Conference in June 2011.

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Cloud storage is a growing tech trend. Making use of cloud computing technology, cloud storage services give you password-protected access to online storage space. You can upload files to this storage space as a backup copy of content from your hard drive, as additional space to supplement your hard drive, or just to make those files available online from other computers or mobile devices.

Apple's cloud storage product, iCloud, is designed to work seamlessly with all your Apple devices connected to the Internet. For example, you can upload photos from your iPhone and access them from your MacBook, upload music from your MacBook to listen to from your iPod Touch, or upload an important document from your Mac desktop to access from your iPad when you're on the go.

But iCloud isn't Apple's first online storage service. MobileMe was iCloud's long-standing predecessor, offering synchronization services for an annual subscription fee. MobileMe's primary purpose was to keep certain files synchronized between multiple devices. This included e-mail, contacts, calendars, browser bookmarks, photo galleries and Apple iWeb and iDisk services. Though MobileMe was tailor-made for Apple products, it also gave users the option to synchronize data from non-Apple computers.

Apple revamped MobileMe and merged its offerings into the new iCloud service. iCloud not only replaces MobileMe, it also adds features, flexibility and free service for up to 5 GB of storage space. In addition, digital products you purchase through Apple's iTunes Store are available from your iCloud account without counting against that free 5 GB. Later, we'll take a closer look at iCloud's features and pricing and how they compare to other cloud storage products.

Like its MobileMe predecessor, iCloud's biggest advantage is that it's integrated into Apple software. That makes iCloud your most convenient cloud storage option, if all your computers and mobile devices are Apple products. Apps you use in both Mac OS X and Apple iOS can connect to your iCloud space and automatically store your data there, including your contacts list and photo gallery. Also like MobileMe, this can expand to include Apple devices used by other family members, too. With iCloud, you can ensure your data is continuously synchronized among your Apple devices while they're connected to the Internet.

Now that you know what iCloud is, let's take a closer look at its features and costs, and how it keeps your data both safe and readily accessible.