Understanding Program Types

I was at an industry-specific training the other day for computer users and was surprised that people who knew all sorts of things about multi-million-dollar deals and often grossed six figures had only the vaguest notion of what went on inside their computers. I thought that I would spend this week, then, discussing the different kinds of computer software.

Computer “hardware” refers to the physical apparatus associated with a computer: the parts we can touch such as the keyboard, mouse, monitor, hard drive and printer. “Software” refers to the coded instructions that the computer executes so that we can do our work. If you think of a home stereo, the “hardware” would be things like the tuner, the cassette deck or turntable, the CD changer, cables and speakers. The software would be the magic that makes it so beautiful music sounds. And just as a stereo can generate sound from different kinds of media: AM radio, FM radio, shortwave, CD, LP or cassette, so computers can run different kinds of programs.

Below are some of the major TYPES of programs one is likely to encounter, along with some explanation of what they do and a few examples. For the most part I shall use the term “program” or “application” to mean the same thing. Adobe Photoshop is one example of a program or application and Microsoft Excel is another. Indeed, pretty much everything within your OS X “Applications” folder could also be called a computer program.

Operating Systems

The operating system is the program that loads when you first turn on your computer and which lets you run all your other program. When you plug in most computers they will run a short program built into the chips themselves (called the “power-on self-test” or “POST”) and then begin to “boot” (from the phrase to ‘pick yourself up by your bootstraps’). When the computer “boots” up into Windows or Linux or Mac OS, it is loading the operating system. Part of the operating system is the “window manager,” which used to be called Windows Explorer in Microsoft Windows and might be KDE or Gnome or Enlightenment in Linux. On the Mac OS the window manager is called the “Finder” and it is the finder which must load before you can see any icons. In OS X the Finder is almost always running in the left-hand or top portion of your “dock.” Other parts of the operating system handle tasks such as communicating with a printer or connecting your computer to the Internet before you can send email or view web pages.

Web Browsers

In 1995 almost no one knew what a web browser was, but today they are the main reason that most people want to own a computer. A web browser is the program you use to look at web pages on the Internet. When you go a website such as Yahoo, a web browser is like the frame around your view of the site. The AOL software includes a web browser, but other web browsers include Safari, Internet Explorer, Netscape Navigator or Firefox. There are literally dozens of them available, but all of them help you to view web pages, and passes other content from web pages (such as podcasts, downloaded files or movies) to programs that can display or play them for you. In theory every web page should look the same no matter what web browser one is using to view it. In practice some web pages work better with some web browsers and some people prefer one browser over another for various reasons. In addition to letting you view and navigate web pages, web browsers can also help you organize your favorite “bookmarks” or memorize usernames and passwords for web sites. If you have a webmail account such as Yahoo or Hotmail, a web browser is also how you view the web page which contains your mail.

Email Clients

In computer terms a “server” is any computer which provides a service on a network. Web servers host web pages, news servers host Usenet and email servers route and hold email until the user decides to retrieve it. “Clients” are programs that retrieve information from servers, and many people read their email, organize it and keep track of their electronic mail with an email client or just “email.” Not everyone uses an email client directly, but some common email clients are Apple Mail.app, Eudora, Microsoft Outlook, Netscape Messenger and Thunderbird. Just as there are many different web browsers for different needs and tastes, so there are different email programs, but all of them perform the basic tasks of letting you compose email, retrieve new email and store or organize email and addresses if you wish.

Chat Clients

Internet “chat” or “instant messaging” is just typing in the same window as other people, more or less simultaneously. The text appears in a window with names to the left, the conversation represented much like a script for a play. To “IM” with someone you must each have the appropriate software and have accounts on compatible chat servers. The most popular chat programs bear the names of the most popular chat services: AOL Instant Messenger (AIM), MSN Messenger, ICQ or Yahoo Messenger. Some programs can log you into several services at once and some (such as Apple’s iChat over Rendezvous) to not require any external service at all. Chat provides a nice way to be available to many people simultaenously and provides a connection faster than email but less of a commitment than the telephone. More and more chat clients include “voice chat” like a telephone call or even “video chat” with high-speed Internet cameras.

Word Processors

Besides Internet, typing out documents is probably the most popular use of computers. A word processor is a program that works similarly to a typewriter, but with more options such as the ability to change fonts and center text, use bold or italics and easily insert things into a document such as page numbers. Some things which were incredibly labor-intensive before computers (such as centering text, correcting mistakes or formatting footnotes) are trivial when done on a word processor. TextEdit is one example of a word processor, with WordPerfect and Microsoft Word being two others.


People forget that it was a spreadsheet, VisiCalc, that made most businesses first want to buy a computer: VisiCalc was “the killer app” that everyone wanted when they bought their first Apple II’s back in the 1970’s. If word processors were an electronic version of the typewriter, spreadsheets were electronic ledger sheets, allowing people to arrange numbers and values neatly and have the computer do the calculations. Some people merely use spreadsheets to organize data (such as inventory or address lists) into tables, but these can also do sophisticated calculations and generate a wide variety of charts and graphs from raw numbers. Lotus 1-2-3 was one popular spreadsheet, with Microsoft Excel another.


A database is also used to arrange information, but usually in more complex ways than a spreadsheet, allowing the same information to be reused in as much or as little detail as needed. Most people who use databases don’t think of them as databases at all, any more than we think of a dictionary, phonebook or card file as a database. Some of the most database programs organize names and addresses (for a mailing list), appointments or financial information. Palm Desktop, iCal and Address Book for OS X are all database programs, as are accounting programs such as Quicken, QuickBooks and AccountEdge. Just as Quicken can keep track of check information in various ways: printing physical checks, tracking the general ledger, remembering payees and sorting income or expenses by category, so can most databases. In addition to storing and filtering and retrieving information, many databases are also used to generate reports such as birthday lists, mailing labels or tax returns. Microsoft Project is a project-management database while iPhoto is a database for images. Two of the more popular database programs for people who want to build their own databases are Microsoft Access and FileMaker Pro.


Just as there are many ways to store, transmit and play movies, so there are many ways to store, manipulate and play with sound or pictures. Media players of different sorts are used to play content created by others and the most popular players include Acrobat Reader, QuickTime, RealPlayer, Flash and Microsoft Media Player. iTunes combines a database program with sound and video files, much as iPhoto does for pictures or iMovie for slides, pictures and video. Some programs such as iDVD, Final Cut Pro or GarageBand are primarily for people who want to create multimedia, which broadly defined on the computer is anything that combines pictures, sound and motion.

Presentation Software

For less sophisticated presentations than might be done in iMovie, there is presentation software. Basically a replacement for the ancient days of the slideshow or slide projector, presentation software allows a public speaker or presenter to put together a series of screens or “slides” which can then be played back as an audio-visual aid. PowerPoint is the most famous example of presentation software, but Apple’s Keynote is another, more sophisticated version. Good presentation software such as Safari allows the material to be reused and exported in a variety of formats: as PDF, prints, speakers notes, DVD or Flash movies.

Graphics Software

Graphics software is of two basic types: vector and raster. Vector graphics are mathematically described collections of shapes such as are used in drafting or graphic design. AutoCad, Visio and Illustrator use vector graphics, which can be enlarged or miniaturized almost infinitely without losing any resolution. Raster graphics are based on individual picture elements (“pixels”) and are largely used in photography or digital painting. Adobe’s Photoshop is the most famous example of a raster graphics program, and can even be used for simple page layout.

Page Layout

If spreadsheets were the “killer app” of the 1970’s and web browsers were the killer app of the 1990’s, page layout programs were the star of the 1980’s as desktop publishing completely changed the way printed media of all sorts was produced. With an Apple Macintosh, PageMaker and a laser printer, a single person could produce work of such high quality as to replace an entire department of typesetters and layout artists. Page layout programs allow one to combine text and graphics on the printed page in ways much more sophisticated than mere word processors. Microsoft Publisher and Apple Pages are two basic page layout programs, with Quark, PageMaker and InDesign being some others. Much of the publishing explosion that erupted after 1985 was because of page layout programs.

Integrated or Modular Software

Much more popular when computer software was more expensive and computer memory was relatively low, modular software contains a little of everything, so that it does more than one thing. ClarisWorks, Microsoft Works and AppleWorks, for example, provided a basic word processor, database, spreadsheet and graphics programs, as well as some basic telephony for connecting to the Internet in the days before web pages. Although the trend has been for companies to generate “suites” of software by bundling programs together into a package such as Microsoft Office or Adobe Creative Suite, some modern programs such as Netscape and Mozilla still combine functions such as web browsing, contact management, email and a basic web-page authoring tool. Microsoft Outlook and Entourage combine a calendar with email, an address book and other tools. The advantage of modular software is that one can learn the basics of one module and understand the basics of several others, or create “documents” that contain many different types of data. “Suites” accomplish this same goal by gradually making the various commands and interface more and more similar between and amongst the programs or encouraging the programs to work more easily together as with Apple’s “iLife” suite and the various programs that communicate with .Mac using iSync.


Fortunately, this is not a huge category on the Macintosh. Malware includes a variety of programs which are designed to do things the user doesn’t intend such as propagate themselves, damage files, alter user settings or collect and report back on a user’s acivities. This category would include “trojan horse” programs, spyware, computer viruses and worms.


There are many many other types of programs, from utility programs that perform maintenance tasks such as scanning for viruses to other types such as voice recognition software, computer-aided manufacturing, optical character recognition and more, but these are the main sorts of software that most people are likely to use on their computers and understand. Watch this space for more basics and suggestions for using each of these basic program types.


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