*How to Open and Look at that Mysterious Computer File* *Publication Date:* November 2003 *Volume:* 39-3 *Author:* Richard Schenkar *Categories:* Practical resources, Computers, Internet Have you ever received a file that you could not open or that looked like gibberish when you looked at it with your word processor? In most cases, that is because the file is in a different format than those recognized by your word processor. Some of these frustrations are easier to solve than others. The best place to start is to look at the name of the file, concentrating on the file extension. That is the two- or three-letter designation to the right of the period in the file name. The easy situations include files with the .pdf file extension (meaning Portable Document Format) that you open with the Adobe Acrobat file viewer available at adobe.com . Many government documents already use the Adobe Portable Document Format. That is why it is probably prudent to download and install that viewer (even for your handheld computer or personal digital assistant). Microsoft PowerPoint presentation files (designated with the .ppt file extension) may be opened with PowerPoint viewers available on the Microsoft website, microsoft.com , or with the Impress presentation application in the OpenOffice software suite, available for free download at openoffice.org . There are viewers on the Microsoft website for Microsoft Excel files (file extension: .xls), Microsoft Visio files (file extensions: .vsd or .vdx), and Microsoft Word files (file extension: .doc). Apple Computer's QuickTime Player, available at apple.com/quicktime , is a multimedia player that will play a number of different formats, including the QuickTime format (with the .qt file extension) and MPEG audio and video format. *Compressed Files* File compression allows you to transmit and receive files faster and squeeze more data into limited storage. Because many resources were developed on small computer systems with extremely limited specifications (especially by today's standards), you will discover many useful materials online in compressed formats. File compression works by eliminating redundancy. The programs create a dictionary and a short reference mapped to each item. That short reference substitutes for the item in the compressed file. By this procedure, the average text file compresses to about one-half its original size. Utilities that compress and expand files (using the .zip file extension) include WinZip (for the Windows operating system), available at winzip.com , Stuffit (for the Apple Macintosh operating system), available at stuffit.com , and PowerArchiver, available at powerachiver . *If things get complex. . .* Most of your frustrating situations you encounter will be handled with the resources already cited. As you push further onto the World Wide Web (and off the Web--into massive text archives not indexed by generally-used search tools), you will encounter files in many different file formats with file extensions different than the ones above. You will need some way to discern the format, obtain the proper viewer, download and install the viewer, and test it to make sure that it is working properly. With those two or three letters of the file extension in mind, start with the Graphics File Formats Page, at dcs.ed.ac.uk/home/mxr/gfx/utils-hi.html (high resolution version) or dcs.ed.ac.uk/home/mxr/gfx/utils-lo.html (low resolution version). From the list of graphic file extensions, pick the one that applies and there is a hypertext link to relevant helpful sites. There is also a helpful FAQ (frequently asked questions) list, a section on explanations of file formats and a comprehensive list of hypertext links. Once the necessary viewers are installed on your system, you might want to test them to make sure they work properly. For that, head to the WWW Viewer Test Page at eng.llnl.gov/document s/wwwtest.html where you can get an instant online test of the operation of viewer you have selected.