Five Essential Characteristics of Cloud

The five essential characteristics of cloud computing are:

On-Demand Self-Service

A consumer can unilaterally provision computing capabilities, such as server time and network storage, as needed automatically without requiring human interaction with each service provider.

The customer is able to use the service (or stop using the service) freely (via a web portal) without direct communication to the service provider.

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).

The service is available through standard network connections (ie. the Internet or private WAN connections), and can be accessed through many kinds of devices.

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 costumer 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 datacenter). Examples of resources include storage, processing, memory, and network bandwidth.

A pool of resources is provided by the service provider, and when a costumer requests a service (for example creates a new VM), the resource to fulfill that request are allocated from the shared pool.

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 appear to be unlimited and can be appropriated in any quantity at any time.

Customers can quickly expand the services they use in the cloud (for example, add new VMs, expand storage, etc) from a pool of resources that appears to be infinite. Likewise, they can quickly reduce their services when not needed.

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 accounts). Resource usage can be monitored, controlled and reported, providing transparency for both the provider and consumer of the utilized service.

The cloud service provider measures the customer's usage of cliud resources, and the costumer can measure their own use as well. Customers are charged based on usage (for example, X dollars per gigabyte of storage per day).