TECHNICAL TIPS

Extensions: - What's in a Name?

By DIANE MCCARGAR

The next time you look at a file on your computer and wonder what it is and where it came from, try looking for an extension. Many file names end with an extension, a dot followed by 2 to 4 letters (e.g. letter.doc). Most Windows programs automatically add extensions to file names. These letters can tell you the type of data contained in a file and sometimes they identify what program was used to create it. They may also tell you the version of the program. If you know what software was used to create a file and your computer has this software, then viewing its contents becomes very simple - run the program and then open the file. If your computer doesn't contain the software or you don't know what software was used, then double-click on the file and see what happens. If the computer can't find or doesn't recognize what program the file came from, then it will ask you to choose from a list of software installed on your computer. Extensions can help you choose the most appropriate software to view a file. Here are some common file extensions:

Text Files
Files that contain only text often end in the extension .txt These documents can be viewed by any word processing program such as WordPerfect, Word, SimpleText or WritePad. Rich Text Format (RTF) is similar to text only, but it also includes some simple formatting information such as fonts and margins. Most word processing programs allow you to view documents saved in RTF format.

Formatted Files
Files that contain text and formatting are normally given an extension unique to the program that was used to create the document. For example, Microsoft Word documents usually end with doc and WordPerfect documents usually end with .wpd. To view these documents, you must have the same software or a similar program that is able to translate files of that format. (Remember, a program is unlikely to be able to translate a file created using newer software.)

Email and the Internet have made it common place for people to share documents. If you have tried to do this in the past, you probably realize how many problems can occur. Maybe, you weren't able to view something because you didn't have the same software or you had an older version of the software. Maybe you could view it, but the text and graphics weren't formatted the way they should be. A new file type called Portable Document Format (PDF) tries to overcome this problem. PDF files are formatted so that they can be viewed and printed the same way on any computer using Adobe Acrobat Reader. Anyone can download Adobe Acrobat Reader free of charge from Adobe's Web site: http://www.adobe.com. Additional software from Adobe is needed to create and edit PDF files. PDF is now becoming the standard format for posting document files on the Internet

Executable Files
Executable files are program files that end in the extension .exe. When you double-click on an exe file this automatically starts a program. These files only work on computers running DOS or Windows.

Web Page Files
Web pages are created in a language called HTML and have html or htm as their extension

Graphics Files
There are many different types of graphic file formats. Graphics Interchange Format (.gif) is one of the most common graphics file formats. JPEG (.jpg) is a compression format often used for photos. TIFF (.tif) is a high-resolution image format. These images can be viewed on a Mac using programs such as JPEGView. On a Windows PC you could use LviewPro. Commercial graphics programs such as Photoshop can also be used to view, create and edit these types of files.

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