Cloud computing or simply cloud refers to the delivery of computing resources on demand, which includes mostly everything from applications to data centers over the internet on a pay-for-use basis. It can be private cloud, public cloud or hybrid cloud. A private cloud is owned and operated by a specific enterprise where as in a public cloud like Amazon AWS or Microsoft Azure, any one can create an account and build up their virtual infrastructure following the rules and regulations of the cloud service provider. A hybrid cloud is nothing but a combination of private and public cloud, where enterprises have most of their infrastructure running on a private cloud and a part of their infrastructure is running on the public cloud. Cloud offers SAAS (Software-As-A-Service), PAAS (Platform-As-A-Service) and IAAS (Infrastructure-As-A-Service).
Considering the public cloud, high performance tier 4 data centers are the basic building blocks or foundation of the cloud infrastructure. Several virtualized data center clusters which are geographically distributed across the globe and interconnected by multiple high speed and redundant communication links that are backed up by multiple power sources and disaster recovery (DR) plans forms the backbone of public cloud architecture. It mainly provides IAAS (Infrastructure-As-A-Service) platform that manages and orchestrates pools of storage, network and compute resources. You can setup an on-demand elastic cloud computing service. It allows end users to provision resources. They are massively scalable infrastructure. Everything is virtualized. Internally, a pool of virtual appliances support the operation and configuration of the cloud itself. It will be having a GUI, web interface for provisioning resources and managing the cloud infrastructure. It will also have high availability and metering of resource usage.
You can setup your own private cloud using open source cloud platforms like Open Stack, Apache Cloud Stack etc.
