We talk of computation as a service bundle when we talk of cloud computing. We aim to use the entire platform, including server infrastructure, computer network, operating system, and software applications, as a service and aim to pay-per-use basis. The situation is like taking a flight to a destination with a small fee where we do not need to be worried about the cost and maintenance of aircraft, airport infrastructure, crew salary, etc. We only pay a fee for the flight tickets, for the service we hire, thus pay for use only.
The whole concept of ‘Cloud Computing’ started with using Software as a Service (SaaS) where application service providers set up their software applications to be used on a pay-per-use basis. Later, the same concept was extended to infrastructure, and we called it as IaaS (Infrastructure as a Service). A natural extension is a Platform as a Service (PaaS), which included hardware, software, and network to give a holistic approach to computing. This inclusive approach to computing, with network and server resources, operating system, and software applications, from one or more vendors and located at one or more locations, working in unison to provide storage, application computing, and manageability, has led to the model called ‘Cloud Computing’.