Cloud computing means storing and accessing data and programs over the Internet instead of ones computer’s hard drive.It is a kind of Internet-based computing that provides shared processing resources and data to computers and other devices on demand through internet.
There are different types of clouds
1. Public Cloud – A public cloud can be accessed by any subscriber with an internet connection and access to the cloud space.
2. Private Cloud – A private cloud is established for a specific group or organization and limitsaccess to just that group.
3. Community Cloud – A community cloud is shared among two or more organizations that have similar cloud requirements.
4. Hybrid Cloud – A hybrid cloud is essentially a combination of at least two clouds, where the clouds included are a mixture of public, private, or community.
Characteristics of Cloud
On-demand self-service: A service consumer can automatically make use of the computing capabilities, such as server processing time and network storage without requiring human interaction with each service’s provider
Broad network access: Cloud Capabilities are available over the network and accessed through standard mechanisms that promote use by heterogeneous thin or thick client platforms such as mobile phones, laptops and PDAs
Resource pooling: The provider’s computing resources are pooled together to serve multiple consumers using multiple-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand. The resource include others storage, processing, memory, network bandwidth, virtual machines and email services. The pooling together of the resource builds economies of scale.
Rapid elasticity: Capabilities can be rapidly and elastically provisioned; it can be quickly scaled out, and quickly scaled in. For the user, the capabilities available for provisioning appear to be unlimited and can be purchased in any quantity at any time.
Shared Infrastructure : Uses a virtualized software model, enabling the sharing of physical services, storage, and networking capabilities. The cloud infrastructure, regardless of deployment model, seeks to make the most of the available infrastructure across a number of users.
Network Access: Needs to be accessed across the internet from a broad range of devices such as PCs, laptops, and mobile devices, using standards-based APIs. Deployments of services in the cloud include everything from using business applications to the latest application on the newest smartphones.
The cloud services can be categorized into software services and infrastructure or hardware services
Software as a Service(SaaS): A SaaS provider gives subscribers access to both resources and applications. SaaS makes it unnecessary for you to have a physical copy of software to install on your devices.
Platform as a Service (PaaS): Consumers purchase access to the platforms, enabling them to deploy their own software and applications in the cloud. The operating systems and network access are not managed by the consumer, and there might be constraints as to which applications can be deployed
Infrastructure as a Service (IaaS) : Consumers control and manage the systems in terms of the operating systems, applications, storage, and network connectivity, but do not themselves control the cloud infrastructure.
Scalability/Flexibility: The most important feature of Cloud computing is its flexibility. Companies can start with a small deployment and grow to a large deployment fairly rapidly, and then scale back if necessary. Also, the flexibility of cloud computing allows companies to use extra resources at peak times, enabling them to satisfy consumer demands.
Access from innumerable options: Another benifit of cloud computing is accessing the environment of cloud not only from the system but through other amazing options. These options are tablets, IPad, netbooks and even mobile phones.
It is Cheap! : low cost always bring smile. This is another thing for cloud computing. Cloud infrastructure eliminates the high software costs of the businesses. Cloud for business removes the huge cost at the front for the servers of the enterprise. Cloud service providers do the system maintenance, and access is through APIs that do not require application installations onto PCs, thus further reducing maintenance cost.