What is cloud computing?

In a nutshell cloud computing allows access to a large amount of computing power in a fully virtualized manner. The aim of this technology is to deliver computing as a utility. Utility computing is a business model of on-demand delivery of computing power ( pay-as-you-go).

Cloud computing provides multiple services initially offered by microsoft, google and amazon based on a model where computing infrastructure is viewed as a “cloud”.

Principle of cloud computing behind this model is to offer computing, storage and software as service.

Professor Dr. Rajkumar Buyya's Cyberhome says “Cloud is a parallel and distributed computing system consisting of a collection of inter-connected and virtualised computers that are dynamically provisioned and presented as one or more unified computing resources based on service-level agreements (SLA) established through negotiation between the service provider and consumers.”

Types of cloud computing

SaaS (Software as a service ): Self- service with zero operations. Software with no installation, no patch, and operations.
IaaS (Infrastructure as a service ): Agile, on-demand infrastructure. Get things based on your business needs. Very flexible.
PaaS (Application as a service): Application-centric with integrated runtime. Building an application stack is not required.
CaaS (Container as a service): Intelligent machinery for diverse workloads. This machinery helps developers handle all types of workloads. It might not be suitable for other environments, though. Ex:- Kubernetes.
FaaS (Function as a service): Pay-per-use code used for execution only. It is used when something is running as it also makes development fast and easy. ( serverless computing )

Summary

In a nutshell cloud computing is an SLA between vendor and enterprise, Venders like AWS, Azure.