What is cloud computing? can you run a site like Ebay off of it?

Can you run a site like Ebay using cloud computing? Does cloud computing not require any servers?What is cloud computing? can you run a site like Ebay off of it?
First I'll answer the 2nd part of your question:-

You can run Ebay like website on cloud services (IaaS). Cloud Computing will definitely require a server.

Gmail, Google Docs %26amp; many Google services are running on the cloud. You can find more info about Google's cloud services from here:
http://www.techno-pulse.com/2011/04/goog鈥?/a>

The biggest IaaS provider Amzon hosts 100s of websites/apps on Amazon AWS (cloud computing).

About Cloud Intro:
Let us simplify this with a simple example: Gmail is a cloud service. Having said that, this doesn't mean that any service hosted on the web is a cloud service. Cloud Computing Services must have following 5 attributes:

---available everywhere i.e. uses Internet technologies, hassle-free, in most cases no installations/downloads etc.
---available on demand i.e. metered like your electric bills.
---can be accessed on any device i.e. device independent.
---Resource Sharing i.e Multi-Tenant (ability of the software to be offered to multiple users),
---Scalable %26amp; Elastic i.e. capacity can be sized up or sized down with in minutes, based on demand. Your business is growing you spin up more servers %26amp; pay only for whatever you use. Come recession %26amp; if your business is shrinking use less number of servers %26amp; pay less. This is as simple %26amp; quick as a simple configuration/settings. (No need to buy infrastructure which may lie idle/unproductive once your business doesn't require them)

A common user will use Cloud SaaS (Gmail, Dropbox etc). Developers %26amp; techies use Cloud IaaS (hosting infrastructure) %26amp; PaaS (development environment).