Tips & Definitions:
Data communications, application of telecommunications technology to the problem of transmitting data, especially to, from, or between computers. In popular usage, it is said that data communications make it possible for one computer to “talk” with another. Telephone circuits are often used to transfer data, although their relatively limited bandwidth makes them relatively slow paths for data. Recent techniques, however, have made it possible to send data over phone lines at rates of 28,800 bits per second and higher. A modem is required for such telephone communications when they occur over standard (analog) telephone circuits. Where cost can be justified, high speed data links are constructed; these are often fiber-optic or coaxial cables designed for wide frequency range, or microwave, radio links. Local-area and wide-area networks link computers together so that they can transfer and share data. Because many computers can be on the network at any given time, techniques such as time-division multiplexing are used; each computer is assigned a short time slot during which it can use the full bandwidth of the network. Packet switching allows a single channel to be used for multiple concurrent transmissions. Data packets contain addresses that indicate the intended destination. To minimize data-communication errors, special codes are used.

Application software is a subclass of computer software that employs the capabilities of a computer directly to a task that the user wishes to perform. This should be contrasted with system software which is involved in integrating a computer's various capabilities, but does not directly apply them in the performance of tasks that benefit the user. A simple, if imperfect, analogy in the world of hardware would be the relationship of an electric light - an application - to an electric power generation plant - the system. The power plant merely generates electricity, itself not really of any use until harnessed to an application like the electric light which performs a service that the user desires. Typical examples of software applications are desktop, word processors, spreadsheets and media players.

Multiple applications bundled together as a package are sometimes referred to as an application suite. Microsoft Office, which bundles together a word processor, a spreadsheet, and several other discrete applications, is a typical example. The separate applications in a suite usually have a user interface that has some commonality making it easier for the user to learn and use each application. And often they may have some capability to interact with each other in ways beneficial to the user. For example a spreadsheet might be able to be embedded in a word processor document even though it had been created in the separate spreadsheet application. User software tailors systems to meet the users specific needs. User software include spreadsheet templates, word processor macros, scientific simulations, graphics and animation scripts. Even email filters are a kind of user software. Users create this software themselves and often overlook how important it is.

System software is a generic term referring to any computer software whose purpose is to help run the computer system. Most of it is responsible directly for controlling, integrating, and managing the individual hardware components of a computer system. System software is opposed to application software that helps solve user problems directly. System software performs tasks like transferring data from memory to disk, or rendering text onto a display. Specific kinds of system software include loading programs, operating systems, device drivers, programming tools, compilers, assemblers, linkers, and utilities. Software libraries that perform generic functions also tend to be regarded as system software, although the dividing line is fuzzy; while a C runtime library is generally agreed to be part of the system, an OpenGL or database library is less obviously so. System software can be stored on non-volatile storage on integrated circuits that is usually termed firmware.