http://www.salesforce.com/cn/cloudcomputing/
什么是云计算？
-----来自salesforce对云计算的解释没有云计算平台之前
像 SAP、Microsoft 和 Oracle 等提供的传统业务应用程序总是过于复杂，而且十分昂贵。它们需要成立一个数据中心，且数据中心内需配备办公空间、电源、制冷设备、带宽、网络、服务器和存 储器。另外，需要一堆复杂的软件堆栈， 以及一支负责安装、配置和运行的专家团队。此外，还需要提供开发环境、测试环境、整理环境、生产和故障转移环境。
当您在数十个或者数百个应用程序上重复受到上述因素的制约时，您就很容易明白，为什么拥有最佳 IT 部门的规模最大的公司仍然无法有效获得所需的应用程序。小企业根本没有任何机会获得所需的应用程序。
云计算平台：一种更卓越的方式
云计算平台是运营企业的一种更卓越的方式。无需您运行应用程序，所有应用程序均在共享数据中心内运行。当使用云服务中运行的任何应用程序时，您仅需登录、自定义、然后开始使用即可。这就是云计算平台提供的强大功能。
如今，许多企业都在使用云服务来运行所有各类应用程序，其中包括 CRM 应用程序、人力资源应用程序、财务会计应用程序以及自定义开发的应用程序等。只需短短数天，您便可启动和运行基于云计算平台的应用程序，这一点令传统商业 软件望尘莫及。由于您无需再为运行它们的全部人员、产品和设备支付费用，因此这类应用程序成本较低。此外，与大多数应用程序相比，这类应用程序更具可扩展 性、更安全、更可靠。另外，云计算平台还将负责软件升级，因此，您的应用程序可以自动获取安全性和性能方面的增强功能和新功能。
您支付基于云计算平台的应用程序费用的方式也将与以往不同。您从此不必购买服务器和软件。利用云服务运行应用程序时，您不必购买任何设备。您需支付的所有费用都已计入可预见的每月订阅费中，因此，您仅需为实际使用的功能付费。
最后，基于云计算平台的应用程序还不会占用您宝贵的 IT 资源，因此，首席财务官会对它格外青睐。这样，您可以集中精力部署更多应用程序、新项目和创新方案。
利润方面：云计算平台是一种极为简单的理念，但它可以对您的企业利润产生极大的影响。
English version:
What is cloud computing?
Life before cloud computing
Traditional business applications—like those from SAP, Microsoft, and Oracle—have always been too complicated and expensive. They need a data center with office space, power, cooling, bandwidth, networks, servers, and storage. A complicated software stack. And a team of experts to install, configure, and run them. They need development, testing, staging, production, and failover environments.
When you multiply these headaches across dozens or hundreds of apps, it’s easy to see why the biggest companies with the best IT departments aren’t getting the apps they need. Small businesses don’t stand a chance.
Cloud-computing: a better way
Cloud computing is a better way to run your business. Instead of running your apps yourself, they run on a shared data center. When you use any app that runs in the cloud, you just log in, customize it, and start using it. That’s the power of cloud computing.
Businesses are running all kinds of apps in the cloud these days, like CRM, HR, accounting, and custom-built apps. Cloud-based apps can be up and running in a few days, which is unheard of with traditional business software. They cost less, because you don’t need to pay for all the people, products, and facilities to run them. And, it turns out they’re more scalable, more secure, and more reliable than most apps. Plus, upgrades are taken care of for you, so your apps get security and performance enhancements and new features—automatically.
The way you pay for cloud-based apps is also different. Forget about buying servers and software. When your apps run in the cloud, you don’t buy anything. It’s all rolled up into a predictable monthly subscription, so you only pay for what you actually use.
Finally, cloud apps don’t eat up your valuable IT resources, so your CFO will love it. This lets you focus on deploying more apps, new projects, and innovation.
The bottom line: Cloud computing is a simple idea, but it can have a huge impact on your business.