A+ Certification / Beginners

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Understanding file extensions

In this section, some of the major types of file extensions you can expect to see within your operating system. By default, file extensions for registered file types are hidden. Registered files types are files that have extensions which already have applications associated with them. To display file extensions within Windows XP, follow these steps:

1. Open any directory window, such as My Computer.
2. Choose Tools → Folder Options.
3. Click the View tab.
4. Clear the check box in front of Hide Extensions for Known File Types.
5. Click OK.

In the sections that follow, we discuss common file extensions and how they are used on your computer.

Executables

Executable files can perform tasks on the system. Table below summarizes some of the file extensions common to executable files.

Executable File Extensions

Extension	Type	Description
.bat	Batch file	Batch files are a series of commands that have been sequentially typed into a text file.
.cmd	OS/2 command file	Command files usually execute with only a command shell interface.
.com	MS-DOS command file	Like the OS/2 command files, these files usually execute with only a command shell interface.
.exe	Command-line or graphical program	This is the most common extension for executable files.
.vbs	Visual Basic Script file	Visual Basic Script files are not executable themselves, but rather require either wscript.exe or cscript. exe to be executed. They are a cross between Visual Basic applications and batch files.

Major Office applications

You need to be familiar with the file extensions associated with a few of the most popular office applications on the market. Some of these extensions are listed in Table below.

Application File Extensions

Extension	Type	Description
.doc	Document File	Document files are usually associated with Microsoft Word, but are sometimes used by installations of WordPerfect.
.dot	Document templates	Document templates for Microsoft Word. normal.dot is the default template for new documents.
.ppt, .pps	Microsoft PowerPoint documents	.ppt files open in the PowerPoint interface and are immediately editable. .pps files, when you double-click them, open directly in PowerPoint Slide Show mode and close as soon as the slide show finishes.
.wks, .wk4	Lotus 1-2-3 worksheet files	The number at the end denotes that a specific version of Lotus 1-2-3 was used.
.wpd	WordPerfect document	This and .doc are common extensions for documents.
.wpg	WordPerfect Graphic	WordPerfect's proprietary graphic format.
.xls	Microsoft Excel document	Spreadsheets associated with Microsoft Excel.