Cloud Computing has a few varied meanings from API services such as twitter to web-based (read cloud-based) email services such as gmail and yahoo.
An even bigger tectonic shift is happening though, in the area of infrastructure and hosting, to cloud based solutions. No longer is provisioning a slow ordering process, followed by a multi-year contract and commitment with an associated high price tag. Now computing resources can be provisioned and "spin-up" in seconds, even allowing for auto-scaling, bringing new computing resources online dynamically as seasonal traffic patterns demand.
- uniquely suited to applications with seasonal traffic requirements
- supports disaster recovery effectively for free
- allows temporary provisioning of test environments
- facilitates auto-scaling of bare metal servers
- no huge budgetary outlay, pay for only what you use
- bring up resources in seconds - supports true agile development
What's more since cloud resources are all provisioned in software through an API, it encourages the treatment of infrastructure as a whole as software. Now the scripts to completely rebuild all of your systems, from spin-up, to package configuration to application configuration can all be done in software, and managed in version control.