On Monday, Amazon launched Amazon Cloud Drive and Amazon Cloud Player, an online storage locker and music player, respectively. What exactly are these new offerings, and what do they mean for consumers? Here a brief guide:

OK, first things first. What exactly is "cloud computing?"
The "cloud" refers to the internet, and "cloud computing" is the process of storing and accessing software and data over a computer network rather than a physical hard drive. While it's existed for years, cloud computing is "quickly becoming this year's cliche among geeks," says Jose Moreno at Newsday. Web-based services, as opposed to those tied to a physical machine, can be accessed from any internet-enabled device in any location — a great advantage. Do you use Google Docs or Apple's MobileMe? You're already cloud computing.

What has Amazon launched exactly?
It's called the Amazon Cloud Drive and Cloud Player. It's essentially an online storage space and web-based music player that users can access via any desktop computer, or their Android phones or tablets (but not their iPhones or iPads). Anyone with an Amazon account gets a 5GB "locker" of free storage to keep music, or any other files in the cloud. Additional storage is $1 per gigabyte for plans at 20GB, 50GB, 100GB, 200GB and 1000GB.

How do you get your music in the locker?
Music you already own must be uploaded manually. Amazon offers a tool that scans your iTunes library and automatically uploads songs to the cloud. If you have a large collection of music, that could take days, says Scott Gilbertson in Wired. An easier option is simply buying music from the Amazon MP3 Store. "Clearly," says Gilbertson, "this is what Amazon would like you to do."

Why didn't Google or Apple already do this?
Amazon beat them to the punch. Both Google and Apple are reportedly working on their own cloud-based music services, and most commentators cite licensing issues, not technical ones, as the reason why these two companies haven't already released their products. Apple is rumored to be working on a cloud-based version of iTunes that would store users' music and movies, streamable from anywhere.

So is this a big blow to Apple?
It is seen as a direct challenge to iTunes' dominance. Analysts estimate that iTunes has a 70 percent share of the digital music market, while Amazon has just 10 or 15 percent. Amazon already provides businesses with cloud services, so it's "well-equipped" to offer consumers cloud-based music offerings.  It's not "particularly innovative," says Gilbertson, but Amazon's cloud "already has Google and Apple beat on one count — it exists."

And the reviews say...?
It's "disappointing," says Gilbertson. "The interface is awkward and looks a bit like Hotmail did when it first launched — primitive." Yes, it certainly isn't "remarkable," says Jared Newman at PCWorld, but it does what a music player needs to do. Read the fine print, says Steven J. Vaughan-Nichols at ZDNet. According to the terms of use, "Amazon can do pretty much anything they want with your files," including letting the recording industry make sure you obtained them legally. If you want to play music from the cloud, "you have to put up with Big Brother."

Sources: Newsday, Wired, Marketwatch, Fortune, PCWorld, ZDNet