Azure

As per Microsoft, “Cloud Computing is the delivery of computing services including servers, storage, databases, networking, software, analytics and intelligence over the internet (“the cloud”) to offer faster innovation, flexible resources, and economics of the sale”.

Source: https://azure.microsoft.com/en-in/overview/what-is-cloud-computing/

As per the Amazon, “Cloud Computing is the on-demand delivery of the IT resources over the internet with pay-as-you-go pricing”.

Source: https://aws.amazon.com/what-is-cloud-computing/

As per NIST (National Institute of Standards and Technology), “Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.”

Source: https://www.nist.gov/publications/nist-definition-cloud-computing

Let’s try to understand it with a simple example. With an on-premises data center, you need to manage every single thing from the hardware purchase and its maintenance, installing the operating system as well as other software, setting up the network, managing the storage capacity, configuration of the firewall, etc. Capital, as well as Operational Cost, is associated while managing the on-premises datacenters. Either you use it or not, you need to pay for licensing of the software, bills, and cost related to the persons who are managing the entire infrastructure. 

Cloud Computing provides an alternative approach to the on-premises data center. Cloud Providers like Microsoft, Amazon, etc. are providing Several Cloud services. These providers are responsible for managing, maintaining the Hardware and provides several services which you can use. Providers allow you to lease the hardware and software resources which are very expensive and you only need to pay when you use it that means you are converting the Capital Expenditure spend on purchasing the Hardware to the Operational expense. Cloud Providers provide an online portal from where you can directly manage computing services, data storage, network, application resources without the involvement of any third person. 

As per NIST, the cloud model is composed of five essential characteristics, three service models, and four deployment models.

Five essential characteristics of the cloud model are:

1. On-Demand Self service

2. Broad network access

3. Resource Pooling

4. Rapid Elasticity

5. Measured service

Three service models of the cloud model are:

1. SaaS (Software as a Service)

2. PaaS (Platform as a Service)

3. IaaS (Infrastructure as a Service)

Four deployment models of the cloud model are:

1. Private Cloud

2. Community Cloud

3. Public Cloud

4. Hybrid Cloud