“The cloud” is a familiar cliché, but when combined with “computing,” the meaning gets bigger and fuzzier. “Cloud” is a metaphor for the Internet, and “cloud computing” is using the Internet to access applications, data or services that are stored or running on remote servers.
Cloud computing comes into focus only when you think about what IT always needs: a way to increase capacity or add capabilities on the fly without investing in new infrastructure, training new personnel, or licensing new software. Cloud computing encompasses any subscription based or pay-as-you-go service that, in real time over the Internet, extends IT’s existing capabilities.
The first layer is important Infrastructure-as-a-Service, or IaaS. Several years ago, if you want to run business applications on your desktop and control your website, you buy expensive servers and other equipment to control local applications and run your business smoothly.
But now, with IaaS, you can outsource your hardware needs to someone else. IaaS companies provide off-site server, storage, and networking equipment, you rent and use it over the Internet. Released from maintenance costs and wasted office space, companies can run their applications on this rented hardware and access it anytime and from anywhere.
The major players in IaaS include Amazon, Microsoft, VMWare, Rackspace and Red Hat.
The second main layer of the cloud is known as Platform-as-a-Service, or PaaS, or you can call it as middleware. The idea behind this category is that the overall development of your business can happen at this layer, save you the time and resources.
PaaS companies provide a wide range of solutions for developing and deploying applications on the Internet, such as virtualized servers and operating systems. This saves money on hardware and also collaboration easier for a dispersed workforce. The Web application management, application design, app hosting, storage, security, and collaboration tools for app development all fall into this category.
Big PaaS players include Google App Engine, Microsoft Azure, Salesforce Force.com, Heroku, Engine Yard, etc.
The third layer of the cloud is software-as-a-Service, or SaaS. This layer is the one you are interacting with in your daily life, and it is always accessible via web browsers. Any application hosted on a remote server that is available on the Internet is seen as a SaaS.
Some SaaS examples include Amazon Cloud Search, Netflix, MOG, Google Apps, Box.net, Dropbox, Apple’s icloud, etc.