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It used to be, most files were paper and kept in file cabinets, binders and notebooks. Today, however, many files are digital, and are kept on a home computer, a business or school server or in Web-based storage.

Many different file types n something like DNA n exist that determine whether a file is an image, word processing document or something else. The reason for these different types is to ensure a file opens in a compatible application that will correctly display it. If a file doesn't open in a compatible application, all that's likely to appear on your screen is garbage characters.

To keep files in working order n so they open in a compatible application n they are assigned a three-letter extension that appears at the end of the file name. Some of these might sound familiar: image files are "jpg" and "gif," among others, while word processing files are "doc" and spreadsheets are "xls."

You're probably already aware of file types and what they do as some extensions have become "words" on their own. If you say, "Send me that word doc or JPG," or, "Save it as a PDF," you're referring to a file type n a Microsoft Word document, an image file or an Adobe Acrobat document.

You might not know a Word document has a "doc" extension or an Acrobat document has a "pdf" extension because some PCs are set up to hide the file suffix. Usually, file types are transparent and you don't need to see or change them n they sit in the background, keeping everything working correctly. You can send a Word document or a PDF to a someone and trust that it will open OK on their PC if they double-click it.

(To change the appearance of file extensions in Windows, go to Tools, then Folder Options, then View, and select Hide or Show File Extensions. On a Mac, go to Preferences in the Finder, select Advanced and check the box for Show File Extensions; sometimes you also have to select the same settings within each application).

Sometimes files types come into play when you update software and your newer or different word processor tells you it can't open old files or gives you a list of programs to try opening it with. This also might happen when you move to a newer PC or one running on a different platform (Windows to Mac, or vice versa), or when you receive a file from someone else via email or on a disk.

Many times, the software you need to import one of these problem files is built into an application. For example, word processors are able to open some documents from other programs if you go to the File menu, select Open, then select the file. You'll see the program working to import the file and, if successful, it will open in a new window for you to name and save in the newer format. This solution works with many other types of applications as well, such as other programs in an office suite, image editors and more.

If a file still won't open, translation software may be the solution. A translator is an application that can reformat a file into one of many different types, allowing you to try to open it in an application in many different ways to rescue the information within. Translation software uses private file details that Microsoft, Apple and other companies have released so products can be programmed to import files.

One company called DataViz makes a variety of file translation software for both Windows and Mac, and I've used the Mac version many times. (In a pinch, I've also used file editor programs as "can openers" to crack open files I don't have an application for or a translation option for in order to salvage the raw text.)

In terms of file preservation for archiving, the life span of a file type is greater these days than in the past. I won't prognosticate on when JPG or GIF files will longer be in use n there must be as many digital images on hard drives around the world as there are wishes and fishes. The more widespread a file type, the more likely it will be usable in the long term, so file types are probably the least of your worries with regard to preservation. There will always be translation software down the road, too.

The most problematic file types are those from proprietary platforms, such as electronic typewriters or hardware from the beginning of the computer era that can't run Windows or isn't Mac based. If you've got files on odd computer hardware, I'd move them to something more modern using translation software.

A new trend in file types that software producers have become more interested in and supportive of is "open" standards n or "open source" n in which anyone can crack open the format structure and see how it works. Open file formats make translating and preservation much easier to deal with.

When it comes to working with different file types, it's not a perfect world. But between having an awareness of the different formats and, if needed, and access to file translation software, many problems can be solved. Follow-up: Everything you need to know about digital file preservation can be found at the Library of Congress's digital preservation site,

Mark Ratledge is an information technology consultant in Missoula. Contact him through his Web site and blog at

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