The term cloud computing came in existence is last decade while the concept and types of cloud computing services existed in one or the other form for past two decades. The name cloud computing is given to specify that organisations don’t have to worry about where there IT Infrastructure and Application Software are hosted, instead organisations can focus on the IT services they need to meet their fast changing customer requirements.

In past three decades business process automation has gone to the extent that IT has become a key part of all business transformation initiatives to help automate and enable the organisations to achieve their goals. IT services are more and more seen similar to utility services that are reliable, scalable and paid by usage. Cloud computing is also focusing on provide IT services as utility while keeping in mind that utility service needs vary from organisation to organisation. E.g. The power supply and water are the generic utility services and full fill basic need of electricity and water for the customer. But as the need for customer varies so the utility services vary and accordingly the service costs. The need of an industrial organisation is different to the need of an individual customer.

Cloud Computing focuses on providing IT services as utility services and has three types of service offerings which are briefly explained below,

SaaS – Software as a Service : SaaS offering covers the full stack of IT from the hardware all the way up to the software application service. The service is focused on pay for use and generally operates on the pay per use based on number of users and duration of use. E.g. Microsoft Office 360 costs $30 per user per month for online office application software usage.

PaaS – Platform as a Service: PaaS offering covers the IT stack up to providing a platform that business can use to build / manager their own applications. This service is also focused on pay for use and operates based on type of platform and number of applications to be run on the platform as well as any value added service additions. E.g. A company offering PHP and My SQL platform that can be used by organisations to build and host their own applications.

IaaS – Infrastructure as a Service: IaaS offering covers the IT stack upto the Infrastructure layer, in simple words up to Operating System level. The service is also focused on pay for use and operates based Infrastructure usage like hardware and storage. E.g. Hosting providers like Rackspace, Amazon and T-systems offering standardized, virtualized and secured infrastructure hosting that individuals as well as organisations can use for hosting their application platform and application software solution.