What is Cloud?

In order to set context to the cloud discussion, it is worth defining what cloud computing is for a simple reason, that it is relatively a new business model in the computing world.

After reviewing literature, I came across some information which refered to a widely recognised definition of cloud computing by the NIST (National Institute of Standards and Technology).
This institute defines cloud computing as...

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.

FIVE KEY CHARACTERISTICS

There are five key characteristics highlighted by the above definition...

1. on-demand self-service
2. broad network access
3. resource pooling
4. rapid elasticity or expansion
5. measured service.

Let us explore these characteristics in detail for a meaningful discussion about cloud:

• On-demand Self-Service - A consumer can unilaterally provision computing capabilities with each service provider such as server time and network storage as and when needed automatically without any human interaction.

• Broad Network Access -  Capabilities are available over the network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms (e.g., mobile phones, tablets, laptops, and workstations).

• Resource Pooling - The provider’s computing resources are pooled to serve multiple consumers using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand. There is a sense of location independence in that, the customer generally has no control or knowledge over the exact location of the provided resources but may be able to specify location at a higher level of abstraction (e.g., country, state, or datacentre). Examples of resources include storage, processing, memory, and network bandwidth..

• Rapid Elasticity - Capabilities can be elastically provisioned and released, in some cases automatically, to scale rapidly outward and inward commensurate with demand. To the consumer, the capabilities available for provisioning often appears to be unlimited and can be appropriated in any quantity at any time.

• Measured Service - Cloud systems automatically control and optimize resource use by leveraging a metering capability at some level of abstraction appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, and reported, providing transparency for both the provider and consumer of the utilized service.