File Extensions

Having understanding file extensions is necessary for future discussions of file applications.

In the Microsoft Windows operating, most files have names with the format filename.ext where .ext is the extension. An extension is not absolutely required but most files have one in their name. Extensions are generally three characters but may be more or less. Their function is to tell the computer what the file type is and what is to be done with the file, (e.g., when you double-click it), The operating system knows what actions are possible for that particular file, which software is supposed to carry out the action, and where on the computer that software is located (the path).

Knowledge of extensions allows a user to make intelligent decisions about how (or whether) to use a file. For example if an extension is “jpg” and is most probability a picture or a graphics file so it is necessary to have a viewing program associated with the file to view it.

The default for Microsoft Windows operating system generally hides the extensions when viewed from Windows Explorer or the START Menu.

To See All File Extensions do the following: Click START

• Click My Computer
• On the Tools menu in My Computer or Windows Explorer, click Folder Options
• Click the View tab
• Clear the Hide extensions for known file types check box

With this box unchecked all file type except hidden and protected system files will be displayed when viewing files. This table lists a few of the most common file extensions and a little information about them. To see a more extensive list go to Internet address: http://www.webopedia.com/quick_ref/fileextensionsa.asp or search the Internet for “windows file extensions”.

Some Examples of Extensions