User:Dan Nessett/Sandboxes/Sandbox 1

The Internet is a term with many meanings, depending on the context of its use. To the general public, the term is often used synonymously with the World Wide Web, its best-known application. But the internet supports many other applications, such as electronic mail, streaming media, such as internet radio and video, a large percentage of telephone traffic, system monitoring and real-time control applications, to name a few. In one respect the Internet is similar to an iceberg. The vast majority of it is out of sight. While distributed applications allow users to utilize internet services, they require a large suite of technologies visible only to the enterprises that provide them. To Internet Service Providers, the Internet identifies these underlying services. In addition, there are internet services that are accessible to the general public, while these same services are provided in restricted environments, such as those in an enterprise intranet, in military and government private internets and in local home networks. Further complicating the notion of an Internet is is the frequent interconnection of public and private networks in ways that allow limited interaction. This article and the subgroup it describes uses the term Internet in the broadest sense. That is, it identifies the applications that provide an interface between users and communications services, those services themselves, public and private instances of application and communications services and the aggregation of private and public networks into a global communications and application resource.

In order to engineer the internet, internet designers and engineers place its services into one of several layers, which in total comprise the internet protocol architecture. While there have been several different protocol architecture schemes, the one with the strongest support consists of 5 layers: 1) the application layer, 2) the transport layer, 3) the network layer, 4) the link-layer, and 5) the physical layer. Each protocol layer utilizes the services of the next lower layer (except the lowest, the physical layer) to provide a value-added service to the layer above it (except for the application layer, which provides services to users). Utilizing this protocol architecture, it is possible to describe how the Internet works.

Web browsers are perhaps the most common user interface in the Internet. Such browsers translate human requests to the [[Hypertext Transfer Protocol], which actually moves data between the browser and a Web server. Consequently, measured solely in terms of percentage of use, web applications are the most frequently used application. The communications services provided by the Internet have no direct human interfaces; every user-visible function must go through a program resident on a client or server computer. There are literally hundreds of different protocols, applications and services that run over the Internet. Virtual private networks interconnecting the parts of individual enterprises, or sets of cooperating enterprises, overlay the Internet. As mentioned previously a wide range of interconnected networks using the same protocols as the public Internet, but are isolated from it, provide services ranging from passing orders to launch nuclear weapons, authorizing credit card purchases, collecting intelligence information, controlling the electric power grid (see System Control And Data Acquisition), telemedicine such as transferring medical images and even allowing remote surgery, etc.]] Many of these applications utilize custom application interfaces that do not involve a web browser. Consequently, internet distributed applications comprise a much larger set than those experienced by the general public.

Internet applications are distributed. That is, they normally comprise elements that exist in spatially separated locations. That means they must exchange data over potentially