Cloud computing is a buzzword that is all the rage today, and is all about an old idea trying to find a new life
In the old, old days of computers, processors were very large, and very expensive. In order to make practical use of them, "dumb" terminals were connected to central mainframes and numerous users connected to and used applications that were stored and run on the mainframe.
Then along came the PC and everyone ran their own programs on their desktops and laptops. Communication networks just passed data between computers, to reduce the traffic loading. There was not enough capacity in the networks to allow graphics data fo be sent over the system.
Now we have the Internet, and people are trying to sell us on the old model again.
Have the applications and processing power on remote machines, accessed over the web, and just access these from your low powered (and cheaper) "cloud machines"
Someone else worries about patches and keeping apps up to date
You can access very expensive programs for a small fee
Your data is on the web, so if your box dies, you have not lost a thing
You are going to pay for access to the apps you want. Even if you don't use them often, you will still be paying a monthly fee
If the web is down, or you don't have access, you are DIW (Dead in the Water)
Some provider decides what apps are available. (Oh - we just canceled your favorite? Gee - we are sorry)
Are you going to trust your provider with all your data? I sure won't
If your provider goes bankrupt - what happens?
At least that is the picture some people (Microsoft) is pushing on it's commercials lately
At a corporate level, cloud computing is something entirely different.
Many companies spend large amounts of money maintaining data centers that are often under utilized. But they have to overbuild, because it takes to long to add capacity if the high end estimates turn out to be true.
Everyone knows they usually do not come true, but no one can take a chance.
Companies like Amazon and IBM rent computing power over the web. You can purchase storage space and computing power on the fly, and deploy virtual machines as needed to meet your computing requirements
Instead of taking months to buy and install hardware, you can have new servers up and running in hours.
Other versions of this happen when large companies set up their own internal cloud, which they then configure as needed.
So cloud computing is different things to different people. But for a lot of people, it's just a buzzword that they use to impress someone else