In the simplest terms, cloud computing means storing and accessing data and programs over the Internet instead of your computer's hard drive. The cloud is just a metaphor for the Internet. It goes back to the days of flowcharts and presentations that would represent the gigantic server-farm infrastructure of the Internet as nothing but a puffy, white cumulonimbus cloud, accepting connections and doling out information as it floats.
What cloud computing is not about is your hard drive. When you store data on--or run programs from the hard drive, that's called local storage and computing. Everything you need is physically close to you, which means accessing your data is fast and easy (for that one computer, or others on the local network). Working off your hard drive is how the computer industry functioned for decades and some argue it's still superior to cloud computing, for reasons I'll explain shortly.
The cloud is also not about having a dedicated hardware server in residence. Storing data on a home or office network does not count as utilizing the cloud.
For it to be considered "cloud computing," you need to access your data or your programs over the Internet, or at the very least, have that data synchronized with other information over the Net. In a big business, you may know all there is to know about what's on the other side of the connection; as an individual user, you may never have any idea what kind of massive data-processing is happening on the other end. The end result is the same: with an online connection, cloud computing can be done anywhere, anytime.
Consumer vs. Business Let's be clear here. We're talking about cloud computing as it impacts individual consumers—those of us who sit back at home or in small-to-medium offices and use the Internet on a regular basis.
There is an entirely different "cloud" when it comes to business. Some businesses choose to implement Software-as-a-Service (SaaS), where the business subscribes to an application it accesses over the Internet. (Think Salesforce.com.) There's also Platform-as-a-Service (PaaS), where a business can create its own custom applications for use by all in the company. And don't forget the mighty Infrastructure-as-a-Service (IaaS), where players like Amazon, Google, and Rackspace provide a backbone that can be "rented out" by other companies. (Think Netflix providing services to you because it's a customer of the cloud-services at Amazon.)
Of course, cloud computing is big business: McKinsey & Company, a global management consulting firm, claims that 80 percent of the large companies in North America that it's surveyed are either looking at using cloud services—or already have. The market is on its way to generating $100 billion a year.
Shutting down regularly is the practical option, but it's not without its downsides. Let's take a look at the pros, cons, and what you can do to remedy the disadvantages.
Lower energy costs - Computers can draw a large amount of power, especially if you're running a high-end desktop. Shutting your machine down when it isn't in use will prevent excessive and unnecessary use of power, wasting less energy and saving you money on your electric bill.
Fewer temporary system issues - Those who keep their machines booted up indefinitely are familiar with the little problems that crop up when a computer is in use for a long time. Strange little problems occur and they're often solved by a reboot. If you're essentially rebooting every day, you're giving your machine a fresh start. This helps avoid minor system issues.
Quiet hours - When your machine is running, it's capable of making noise. The sounds of the fans can be bothersome if you're sleeping in the same room, but you also run the risk of the computer playing and alert or other sound unexpectedly. This is easily rectified by muting your sound every night, but you run the risk of forgetting. (Of course, you can automate that process on Windows and OS X pretty easily.)
A longer-lasting machine - While you can never really know when your computer is going to fail, less stress placed on its components will contribute to a longer life. You still have to keep it clean, dust-free, and well-maintained, but less activity can help your hardware last longer.
Inconvenience - The biggest disadvantage of shutting down and booting up on a daily cycle is that it's inconvenient. You have to get everything in order to shut down each night and wait to start up in the morning. On top of that, if you forget to boot up and need to access your machine while you're, say, at the office, you won't be able to because it's offline. This problem is easily solved by automated the shut down and start up process. Doing so puts your computer on a schedule so you won't have much of an inconvenience at all.
Energy used for nothing - While you certainly save energy by shutting down your machine, it'll still draw power when off. While an operating desktop would draw a lot more, it would, at least, be capable of doing something while you're away. This problem is easily remedied, however, with a power-regulating socket like the Belkin Conserve ($10). Alternatively, if your desktop supports it, you can use it as a USB device charger overnight so that small power draw isn't going to waste.
You can just hibernate instead - Why shut down when you can hibernate? Hibernation draws about as much power and saves the current working state of your machine so you can resume right where you left off. This is a standard operation for Windows machines, but OS X can use it, too. Apple calls hibernation "Safe Sleep," and it's only regularly employed to laptops when the battery levels are critically low. You can enable this feature at will, however, with apps like SafeSleep and SmartSleep. You can also save power by simply sleeping your computer, which has the advantage of waking up faster (although if you're using an SSD that gain is negligible), but the power consumption is considerably higher. To get a specific idea of how your devices consume power in their various modes, check out this comparison table.
Never Shutting Down
Keeping your computer powered on is the more convenient option. It offers a few distinct advantages that can save you a bit of time and frustration, but also has a few major downsides of its own.
Your machine's always ready to go - It's nice to be able to sit down at your machine and just start working without any setup necessary. Such a luxury comes at a cost—a higher electric bill—but that may be worthwhile depending on your needs.
Your computer can work while you sleep - There are plenty of ways your computer can work while you sleep. It can perform tasks like backup, system maintenance, video encoding, software updates, downloading, uploading, and virtually anything else it can do without your presence. This is a great opportunity to perform intensive tasks when they won't encumber your work.
Run a server - If your computer's on all the time, you can use it to serve up whatever you want. Perhaps you just want the machine to be remotely accessible while you're away from home, or you'd rather host a web site from your house. Whatever the case may be, if you're computer's always online you can serve up most anything.
Heavy power usage - Running your computer 24/7 draws a lot of power. If there's any reason to turn your machine off with any regularity, it's to avoid wasting resources and saving some money on your electric bill.
Rebooting can be a pain - If you're not accustomed to shutting down regularly, the rare reboot can be pretty annoying. Aside from just feeling more like an inconvenience, you'll never be prepared to shut down. If you have several documents, browser windows, applications, and services running, you probably do not have a process in place to easily suspend everything when necessary. OS X Lion (and Mountain Lion) users have the advantage of the Resume feature, which allows you to restore the computer to the working state it was in before shutting down, but that only works perfectly if all your apps support it. Rebooting isn't some horrible, horrible thing, but it is an inconvenience if you're not used to it.
Backed up your data?
A complete system backup, such as a disk image, will help you recover quickly from a drive failure or other catastrophe, but it adds the expense of a second hard drive (or potentially extensive disc swapping if you use your optical drive). The best time to create a drive image is immediately after you reinstall Windows and get your applications running again. An image containing a patched copy of Windows and all your favorite programs configured the way you want them is a very useful thing to have at hand.