Computer Concepts and Terminology

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Computers seem to perform amazing feats as they process information and display output almost instantly; but behind the scenes, they are really very simpleminded devices. All they do is plod along executing long strings of instructions that were previously written by a clever human programmer. The thing that makes a computer’s performances seem so amazing is that it executes these instructions very, very, very quickly, accurately, and tirelessly. Computers aren’t smart; they are just FAST.

But computers can’t do ANYTHING without step-by-step instructions written out for them. These lists of instructions are called programs. Programs (and the associated data) are known as software. Software needs to be installed onto a computer before it can be used. Software is often sold in sets of several programs and associated data called a software package, and typically comes on a CD-ROM or may be downloaded from the Internet. The Microsoft Office Suite is such a collection of programs and data that allows users to manipulate words, numbers, and data.

There are two major categories of software: System software and Application software.

System Software

System software controls a computer’s operations and manages a computer’s resources. System software includes the operating system, utilities, and computer programming tools.

The operating system (OS) controls the allocation of hardware resources such as memory space and CPU processing time, and handles the basic input and output (I/O) for data flowing from and to storage devices (such as hard disks) and peripherals (such as your keyboard). The operating system allows application software to access system resources without the applications having to know the details about the system hardware. The operating system often allocates resources and processing time between several programs which are running at once, which is called multitasking. Multitasking allows you to perform multiple tasks at the same time, such copying a chart from an open Excel document and pasting it into a report you have open in Word, all while your web browser is downloading a large file from the Internet in the background. It is the OS that plays traffic cop in this situation, deciding which program gets time on the CPU when, and handles the flow of data.

The operating system also includes software that provides the user with a operating environment for interacting with the computer. An operating environment could be a command-line interface (requiring the user to type in commands to control the computer), or it could be a graphical user interface (GUI, pronounced “gooey”) that allows users to interact with the computer using a mouse to point and click on icons, buttons, menus, etc.

IBM PC computers originally used the PC-DOS operating system (also sold by Microsoft to other PC users as MS-DOS). DOS is a general term that means “Disk Operating System” and old examples include DOS 3.3 for Apple II computers, and TRS-DOS of Radio Shack TRS-80 computer. However, when most people use the term DOS, they are referring to some version of Microsoft’s DOS for the PC — just as most people use the general term “PC” (which just means personal computer) to refer specifically to the IBM-PC and the PC-compatible computers descended from it.

Most PCs today use some version of the Microsoft Windows operating system (such as Windows 2000 or Windows XP). Windows includes a GUI user environment. A smaller number of PCs use the Linux operating system (a Unix-like OS).

Macintosh computers use some variation of the Macintosh OS, which is a GUI operating system. Older macs may use Mac OS 9, but newer Macs use Mac OS X (pronounced “O S ten”). OS X is built on top of FreeBSD, a Unix-like OS.

High-end microcomputer workstations, file servers, and mainframes often run some variation of the Unix operating system.

System software also includes the software needed to access a peripheral device connected to the computer. Such software is called a device driver, and it controls I/O to the peripheral. The device drivers may come already installed in the OS, or you may have to install or update a driver when you add a new peripheral device.

System software may also include security software, such as Virus checkers and firewalls. A virus checker searches files for potentially harmful programs such as viruses, worms, or trojan horses that are written by malicious programmers. Viruses and similar programs can perform disastrous activities on your computer system, such as erasing your hard disk. To be safe, you should scan all downloaded files and messages on your PC (anti-virus software can automatically do this) and never run any e-mail attachments if you don’t know what they are. (Note: There are vastly fewer viruses that affect Macintosh computers than affect PCs.) A firewall, or similar program, protects your computer from unauthorized access over a network or telecom connection.

Utilities are programs that perform a very specific task, usually related to managing system resources such as disk drives, printers, etc. Unlike application software, utilities tend to be smaller in size and perform activities related to the computer system (scanning for viruses, manipulating file settings, scanning for disk errors, etc.). Some utilities are memory-resident programs that are loaded into RAM and operate in the background.

System software also includes the tools used to write other programs. These include compilers, assemblers, and debuggers for various computer programming languages. A programming language allows a person to write computer instructions in a language that is easier for a human to understand, but which is then converted into the low level numerical instruction codes that a computer processor unit can execute. Some programming languages include C, C++, Java, FORTRAN, COBOL, PASCAL, BASIC, Visual Basic (and such scripting languages as JavaScript and Perl).

Application Software


System software
   Operating systems
Application software
   Word Processing



Application software runs on top of the operating system and allows the user to perform a specific task, such as word processing a letter, calculating a payroll in a spreadsheet, manage a database of information, reading e-mail messages, or manipulating digital photographs. Most applications allow the production and editing of documents (which are the data files created by the application programs). The document files (such as a report created in Word, or a PowerPoint presentation, or a budget spreadsheet) can then be printed, displayed on a screen, or transmitted to other locations.

Applications (and other programs) are stored on your PC as executable files (they contain program steps that the computer can execute); documents are stored as data files.

Some common applications used on personal computers include:


A word processor (such as MS Word or Wordperfect) allows you to enter and format text (as well as some graphics) to create reports, letters, etc. Formatting options include changing the text size, font (typeface), line spacing, and page margins. You may also define styles that are named formatting specifications that allow you to apply and update consistent formatting throughout a long document. You can also use document templates that contain pre-made formatting, styles, and content to allow you to create a document quickly without repeating work unnecessarily. Unlike the first word processors, modern versions use a “what you see is what you get” (WYSIWYG) approach wherein the display on the screen tries to mimic as closely as possible the printed result you will get.

Word processors also handle block operations on chunks of text, such as copying, cutting, and pasting paragraphs or lines (the blocks of information) from one place to another. Word processors include dictionary software to perform spell-checking (and can also do grammar-checking and act as a thesaurus to provide alternate words of similar meaning). Word processors also incorporate functions to search your document contents, or to search & replace one word with another. You will usually find clip art (small pre-made graphics) collections available in most word processors.

In fact, many of the functions above (copy & paste, search, defining styles, etc.) are also available in most of the applications discussed below. Word and the other products of the Microsoft Office Suite of programs (including Excel, Access, and PowerPoint) can exchange data using OLE (Object Linking and Embedding). This integration of the programs allows you to copy a chart from Excel into a Word document, but have the chart remain linked to the original data; if you open the Excel sheet later and change the numbers, the chart in Word will also reflect that change.


Desktop Publishing software (such as QuarkXPress and Adobe InDesign) go beyond word processors, giving you more control over the typesetting and graphic placement of a document. DTP software is used to layout books, magazines, newsletters, complex reports, etc.


Spreadsheet software (such as MS Excel) allows the user to do numerical calculations and produce charts of the results. In a spreadsheet program, the user works in a worksheet consisting of rows and columns (labeled with numbers and letters). The intersection of each row and column is a cell that can contain text, numbers, or formulas. The formulas use the contents of other cells to calculate new results; but the formulas use the cell reference (the row & column location of the cell) and not the contents of the cell — so if the contents of a cell is changed, all dependent formulas automatically recalculate their results. This gives the user to perform “what if” experiments with a complex calculation (“How will our bottom line profits change if we increase our advertising budget by 10%? By 20%?”). Business and financial people love spreadsheets.



Database management software (such as MS Access or FileMaker Pro) allow users to manipulate large amounts of information and retrieve any part of the information that is of interest. A structured database contains data tables that are arranged in a uniform structure of records and fields. An example would be a listing of a company’s customers (and the information about each one), and a listing of all orders placed by those customers. A different type of database is free-form, and does not have the rigid structure for categorizing the information (the World Wide Web, for example, is a huge collection of data archives with no common structure).


Graphics software (such as Adobe Photoshop and Illustrator) are used to create digital media art images and illustrations, or to edit digital images from scanners or digital cameras.


Presentation software (such as MS PowerPoint) is used to create presentations of slides containing text and graphics (and also incorporating sound and visual effects). These presentations can be projected from a computer display projection unit, or the slides can be printed out onto transparencies.


Web authoring software (such as Dreamweaver or GoLive) allow users to create complex web pages without the user having to know XHTML or CSS or JavaScript. The user simply inserts text and graphics into a WYSIWYG editing window to layout the material as desired, and the application software write the necessary web page code in the background.

Integrated software packages (such as AppleWorks or Microsoft Works) combine several different application program functions (such as word processor, spreadsheet, database, graphics, presentation) into one application. The individual modules of the packages are not as powerful as the separate applications in the MS Office Suite, for example, but they may provide the home user with the functionality they need at a much cheaper price.      
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Last update: August 29, 2016 7:27 PM