Cloud computing is a technology that delivers all computing infrastructure hardware and software, shared resources and information to computers over a network. In order to maintain the data and applications, it uses internet and remote servers. Users can access cloud applications through a web browser or from mobile applications. Business software and data can be stored on servers at a remote location. The cloud computing technology has made a geographical shift in the location of data from personal computers to centralized server or cloud.
A public cloud provides services to anyone over the internet whereas a private cloud is a centralized network that supplies services on the hosted device only to a limited number of people.
Some basic and widely used examples of cloud computing are Facebook, Orkut, Gmail, Yahoo mail etc. The cloud computing services are broadly categorized into 3 models
Infrastructure as a service (Iaas): It is a provisional model where the organization or cloud providers outsource the resources such as storage, hardware and network on a physical or virtual computer. Iaas providers supply the resources from a large pool of their data centers only on demand. It allows a company to pay as much as they use. The usage may include electricity, fuel and water. It is also referred as utility computing.
Platform as a service (Paas): Paas is a category of cloud computing service and this layer lies between Iaas and Saas. The services such as hardware, operating systems, storage and network capacity are hosted on cloud and accessed over the internet. Paas services develop web applications without installing any development tools and can also test, run and deploy the applications to a cloud hosting provider without any administration skills and specialized systems.
Software as a service (Saas): A software distribution model where the applications, software and its associated data are hosted on a centralized server and end users can access it through a web browser over the internet. It is an on demand model where the software can be provided based on subscription. For many business applications such as customer relationship management, accounting, enterprise resource planning and content management, Saas has become a common delivery model. It allows the businesses to be even more mobile and collaborative with the latest cloud computing technology. Saas software services range from handling web based emails to database processing.