Cloud Computing is a general term used to describe a new class of network based computing that takes place over the Internet,
- basically a step on from Utility Computing
- a collection/group of integrated and networked hardware, software and Internet infrastructure (called a platform).
- Using the Internet for communication and transport provides hardware, software and networking services to clients
These platforms hide the complexity and details of the underlying infrastructure from users and applications by providing very simple graphical interface or API (Applications Programming Interface).

In addition, the platform provides on demand services, that are always on, anywhere, anytime and any place.
Pay for use and as needed, elastic
- scale up and down in capacity and functionalities
The hardware and software services are available to
- general public, enterprises, corporations and businesses markets
Cloud computing is an umbrella term used to refer to Internet based development and services

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Shared pool of configurable computing resources

On-demand network access

Provisioned by the Service Provider

Cloud computing is a model for enabling convenient, on- demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services).
It can be rapidly provisioned and released with minimal management effort.
It provides high level abstraction of computation and storage model.
It has some essential characteristics, service models, and deployment models.

Why cloud computing could be successful when other paradigms have failed?

It is in a better position to exploit recent advances in software, networking, storage, and processor technologies promoted by the same companies who provide cloud services.
It is focused on enterprise computing; its adoption by industrial organizations, financial institutions, government, and so on could have a huge impact on the economy.
A cloud consists of a homogeneous set of hardware and software resources.
The resources are in a single administrative domain (AD). Security, resource management, fault-tolerance, and quality of service are less challenging than in a heterogeneous environment with resources in multiple ADs.

Cloud Computing Concepts and Models

Cloud provider
- Organization that provides cloud-based resources
- Responsible for fulfilling SLAs for cloud services
- Some cloud providers “resell” IT resources from other cloud providers Example: Heroku sells PaaS services running atop of Amazon EC2
Cloud consumers
- Cloud users that consume cloud services
Cloud service owner
- Both cloud providers and cloud consumers can own cloud services
- A cloud service owner may use a cloud provider to provide a cloud service (e.g. Heroku)

Cloud resource administrator
- Administrators provide and maintain cloud services
- Both cloud providers and cloud consumers have administrators
Cloudauditor
- Third-party which conducts independent assessments of cloud environments to ensure security, privacy, and performance.
- Provides unbiased assessments
Cloudbrokers
- An intermediary between cloud consumers and cloud providers
- Provides service aggregation
Cloudcarriers
- Network and telecommunication providers which provide network connectivity between cloud consumers and providers