What is cloud computing?

What is cloud computing?

From a physical point of view, the cloud is a bunch of servers, storage, networking hardware and software connected to the internet.But even as cloud computing continues to gain popularity across the world, many in the technology business still have difficulty explaining what makes cloud computing special and how it’s different from earlier computing models, such as the grid, virtualization or software as a service.Widespread “cloud washing” hasn’t helped. Companies have been using the term to describe anything remotely associated with technology in an effort to cash in on cloud popularity. Cloud computing has been compared and sometimes equated to the following:

• Client–server computing

  In the client-server model, client computers and server computers communicate with each other over a network.
  This model is similar to cloud computing only in that clients interact with servers to request resources. There are many other characteristics, such as on-demand self-service and elastic scalability that distinguish cloud from client-server computing.

• Mainframe computing

  In both the mainframe and cloud models, you log on to a virtualized resource to get access to your applications and data, but that’s where the similarity ends.
  The mainframe is a virtualized monolithic host for computing resources; whereas the cloud pools compute resource from multiple independent computing devices.

• Grid/distributed computing

  Grid computing loosely couples heterogeneous, often geographically- dispersed computer networks. A cloud can incorporate a grid, but a grid is not a cloud. Cloud computing enables you to self-serve and meter on-demand services to pay only for what you use.

• Utility computing

  Utility computing describes a computing model that delivers resources, such as compute cycles and storage, as a metered service.
  Utility computing also called measured services, is one of five essential cloud characteristics defined by the National Institute of Standards and Technology (NIST). However, the cloud is much more than a subscription service.

• Managed services

  Managed services describe the outsourcing of IT service management to a third party. Those services can include cloud services.

• Software as a Service (SaaS)

  In the SaaS model, you can subscribe to applications that run on cloud infrastructure. However, SaaS is just one of the cloud computing services you can subscribe to. Others include infrastructure as a service (IaaS), platform as a service (PaaS) and desktop as a service (DaaS).

Cloud computing shares characteristics with all of the above, but none of them — by themselves — completely describe cloud computing.