INTRO: In the past, computing tasks such as word processing were not possible without the installation of application software on a user...
In the past, computing tasks such as word processing were not possible without the installation of application software on a user's computer. A user bought a license for each application from a software vendor and obtained the right to install the application on one computer system. With the development of local area networks (LAN) and more networking capabilities, the client-server model of computing was born, where server computers with enhanced capabilities and large storage devices could be used to host application services and data for a large workgroup. Typically, in client-server computing, a network-friendly client version of the application was required on client computers which utilized the client system's memory and CPU for processing, even though resultant application data files (such as word processing documents) were stored centrally on the data servers. Multiple user licenses of an application were purchased for use by many users on a network.
Cloud computing differs from the classic client-server model by providing applications from a server that are executed and managed by a client's web browser, with no installed client version of an application required. Centralization gives cloud service providers complete control over the versions of the browser-based applications provided to clients, which removes the need for version upgrades or license management on individual client computing devices. The phrase "software as a service" (SaaS) is sometimes used to describe application programs offered through cloud computing. A common shorthand for a provided cloud computing service (or even an aggregation of all existing cloud services) is "The Cloud".
Any computer or web-friendly device connected to the Internet may access the same pool of computing power, applications, and files in a cloud-computing environment. Users may remotely store and access personal files such as music, pictures, videos, and bookmarks; play games; or do word processing on a remote server. Data is centrally stored, so the user does not need to carry a storage medium such as a DVD or USB flash drive. Desktop applications that connect to internet-host email providers may be considered cloud applications, including web-based email services.
How it works
A cloud user needs a client device such as a laptop or desktop computer, pad computer, smart phone, or other computing resource with a web browser (or other approved access route) to access a cloud system via the World Wide Web. Typically the user will log into the cloud at a service provider or private company, such as their employer. Cloud computing works on a client-server basis, using web browser protocols. The cloud provides server-based applications and all data services to the user, with output displayed on the client device. If the user wishes to create a document using a word processor, for example, the cloud provides a suitable application running on the server which displays work done by the user on the client web browser display. Memory allocated to the client system's web browser is used to make the application data appear on the client system display, but all computations and changes are recorded by the server, and final results including files created or altered are permanently stored on the cloud servers. Performance of the cloud application is dependent upon the network access, speed and reliability as well as the processing speed of the client device.
Since cloud services are web-based, they work on multiple platforms, including Linux, Macintosh, and Windows computers. Smart phones, pads and tablet devices with Internet and World Wide Web access also provide cloud services to telecommuting and mobile users.
A service provider may pool the processing power of multiple remote computers in a cloud to achieve routine tasks such as backing up of large amounts of data, word processing, or computationally intensive work. These tasks might normally be difficult, time consuming, or expensive for an individual user or a small company to accomplish, especially with limited computing resources and funds. With cloud computing, clients require only a simple computer, such as netbooks, designed with cloud computing in mind, or even a smartphone, with a connection to the Internet, or a company network, in order to make requests to and receive data from the cloud, hence the term "software as a service" (SaaS). Computation and storage is divided among the remote computers in order to handle large volumes of both, thus the client need not purchase expensive hardware or software to handle the task. The outcome of the processing task is returned to the client over the network, dependent on the speed of the Internet connection.