We should get back to what computers are.
What are computers?
Computers are data stored in a memory, maybe on a disk, and it's also computations, and these computations are done with processors
you are used to your personal computer,so what is in your personal computer?
There are memory banks, a disk, and there is also a processor, all this makes computations, and you have it all at home.
the Cloud is like saying: "rather than having all this at home, I will move part of this work someplace else, somewhere in the clouds.
What does clouds mean?
It means a data centre, probably on the other side of the world, in a country i don't know.
The word Cloud comes from a picture, the image for the network, for Internet, is a cloud.
So if you put your computations, your data on the Internet, you are going to put it in the cloud, so we speak of Cloud computing.
In fact, there are no clouds at all, it's very much physical, there are computers and disks.
They're simply outside your house, someplace around the world that you don't know about.
To get a good grasp of the Cloud, you have to understand how it was achieved.
It was achieved, first and foremost, thanks to ultra-high-speed networks, networks that connect your company or your house with those data centres scattered around the world, in high-speed networks.
Second, the costs for the computers, the disks and storage costs have largely become marginal, in other words, the cost have shrunk considerably.
So it is now possible to build and to concentrate in those centers a whole arrays of processors, storage, etc.
and to move this infrastructure somewhere else.
So in the first place, the Cloud is a physical infrastructure with physical networks and real machines,  and a considerable amount of storage.
That's what it is in the first place. So the technical difficulty when talking about the Cloud, is to get these enormous data warehouses running, those gigantic computer warehouses.
Let's just speak about two problems, which may well be the most critical ones.
the First problem, these computers generate heat so they need to be constantly air-conditioned, so huge progress has been made for air-conditioning those data centres.
The second problem is equipment or software breaking down  rest assured that if you have a computer, statistically, your chances to have any equipment or software breakdown are high, it can be anything.
So if you put a million computers in the same place, a million processors in the same warehouses, you have a tremendous probability of failure.
So you have to develop techniques in order to be able to keep functioning and avoid a general shutdown because of a failure
So that app you are running may very well be running on a computer that is going to break down. But you won't even notice, because maybe you'll have to wait a second or two, but your app will keep running on another computer, or another disk.
So that's the bit of magic, I use the word magic but in fact there's nothing magical about it, because it's basically a lot of technology, and a lot of algorithms that were developed to get all this running.
When you store data in the Cloud, the first advantage for you is a safety warranty, your data cannot disappear because it is probably duplicated in several places, maybe in several data centres, but in any case on several computers.
So even if a computer or a disk breaks down, you will still be able to retrieve your data.
At home, anything can happen, your computer could break down, your house could burn.
But here you have a kind of data protection warranty, protection against intrusion as well,
it's not 100% guaranteed, but let's say that they still know how to defend themselves against hackers better than you do.
So that's the first thing.
The second advantage for a company is to be able to make management savings.
Well it's difficult for a company, you have to buy computers, you also have to have system engineers managing all this and that's not the company's core business.
Let's say you're a construction company, you're not in the business of running computers.
So by moving them into the Cloud, you outsource your IT department, in a way, and you allow other people, system engineers that don't even belong to your company, to manage that for you.
So those are the benefits of the Cloud.
The drawbacks are that, in a way, you lose control on what you're doing.
I mentioned a lot the Cloud's good sides, but there are also a bad sides, the first of them being the  ecological problems it generates, because when you store your data far away from home,  you will waste electricity by retrieving them, to get them back home.
That's the first point.
There's another thing bothering me a bit, it's one the the Cloud's underlying philosophy, which is data centralization.
We centralize computations and data.
At the end of the day, there are a few companies that will ultimately own all personal data of every individual throughout the globe in gigantic data centers.
This is in contradiction with  one of the founding philosophies of the Internet for example, which was based on decentralization,on keeping things local.
Decentralization has a lot of benefits, it makes you more self-sufficient, and it saves electricity as well.
So you can say that concentrating all these computations in data centers does not only have positive aspects.
We could figure out ways to create Clouds that are much more decentralized, much more individualized, that means combining all our computation power.
The computers you have at home, your TV set for example, is a computer, and all those things, and those computers could be brought together to create a Cloud,Cloud computing.
That presents many benefits.Let's take video, for example. Rather than getting the movie or video you want to watch tonight at the other side of the world, and so generating considerable energy costs,  maybe you could find that video on your regional or local cloud
at one of your neighbors who maybe doesn't even know he's going to give you that film, but that way you will save considerable amounts of energy and maybe get back the Web's original spirit, which is decentralization.