Is the cloud just another name for web hosting?

Just trying to make sense of what the cloud service is all about. I know Microsoft is one provider that provides a hosting service, where you can host your application on their servers. So how is that different from the good ol web hosting that we've been doing all this while? From what I've read so far I cant co开发者_JAVA技巧nclusively say cloud is something more.

So, is it just that? A new name for the same old thing?

There are 2 qualities that tend to be associated with cloud services, although even these associations are quite loose.

On-demand resources

Rackspace, Amazon, and Microsoft offer services which can scale down to very small sizes, and they can scale up to incredibly large architectures with a modest amount of work (services such as Rackspace's CloudSites don't require any work at all to scale.)

Virtualization

This feature goes hand in hand with the on demand resources. Providers make use of layers of virtualization to offer scalable, shared, secure solutions. You pay for a certain number of computational cycles, bandwidth, or memory, but you never directly interact with any hardware, only the virtualized environment made available by your provider.

This is an oversimplification, but hopefully it helps.

The idea behind cloud computing is that your solution can scale across an arbitrary number of nodes, which is handled by the cloud provider themselves. The advantage of running a site in the cloud is that during times of high load you can easily add servers and scale horizontally. As opposed to traditional web hosting, where you buy new servers and potentially own them forever, in the cloud you only pay for resources as you use them. If you need to scale up temporarily, you only pay for servers for as long as you need them, then when you scale back you don't have to keep paying to run expensive equipment that's just sitting idle.

"The cloud" isn't just simply putting your app on someone else's machine, it's using a distributed computing platform that happens to be online "in the cloud" (yay marketing!).

Very nice description of Cloud computing courtesy of Nathan: Difference between cloud computing and distributed computing?

Cloud computing is a rather vague marketing term, but it usually refers to using applications which are hosted on another companies servers, accessed via the internet, e.g. web filtering via proxies "in the cloud". It's also sometimes called "Software as a Service" (SaaS)