file extension

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file extension

This article is provided by FOLDOC - Free Online Dictionary of Computing (


(1) See domain extension.

(2) A software add-on. For example, extensions add functionality to Firefox and Chrome Web browsers.

(3) Prior to Mac OS X, an executable module that enhanced the Mac operating system. The Windows counterpart is a "dynamic link library" (see DLL).

(4) Apple enhancements starting with iOS 8 and OS X Version 10.10 that enable apps to share functions in other apps. See "iOS 8" in iOS versions.

(5) A file type that is appended to the end of a file name. All executable programs in the Windows and Mac worlds use extensions: .EXE in Windows; .APP in Mac (see APP file). In the Unix/Linux environment, "executables" do not use an extension, but no matter which environment, "data" files have extensions. For example, a file with a .DOC or .DOCX extension is a Microsoft Word document. A file with a .JPG extension is a JPEG image.

Prior to Windows 95, extensions were limited to three characters. Starting with Windows 95, they can be very large (254-260 characters depending on Windows version); however, they are kept small in practice.

Common Extensions and Exhaustive Lists
In this encyclopedia, more than 500 common file extensions are listed under the terms "extension," followed by their first letter such as extension a, extension b and extension c. However, there are websites that catalog many more, including the most obscure; for example, visit See Win Show file extensions, dangerous extensions and graphics formats. See also domain extension.

Win Show file extensions

New installations of Windows default to hiding the file extension when file names appear in Explorer windows and Open/Save dialog boxes in applications. However, this important element of the file name can easily be made visible, and it is one of the first things a user should do after installing Windows. See extension.

Windows 8.1 and 10
1. Launch Explorer and select View.
2. Check File name extensions.

Windows XP and 7
1. Launch Explorer and select Tools/Folder Options/View
2. Uncheck Hide extensions for known file types.
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References in periodicals archive ?
In addition to looking at file extensions, the solution examines the data within the file (e.g., verifying text is indeed text, numbers are numbers) regardless of what the file is named.
In my opinion, the absolute worst issue is that in so many installations the default is to check 'Hide file extensions for known file types.' Simplistically, as you are no doubt aware, what we commonly think of as the 'file name' in Windows is actually composed of two parts.
--If the file is found, it will be written using the unit's UIC followed by a 2-digit number and a file extension ".001" in ASCII text.
The file extension of a computer file indicates the format of the file.
Is there a way I can change the .eml file extension to an image extension, ie; jpg or gif.
Normally referred to as an ASCII file, your text-only resume can be saved in three different ASCII formats: ASCII Plain Text which has a .txt file extension; ASCII Rich Text which is recognized with an .rft file extension; and ASCII Hypertext (Hypertext Markup Language) which has an .htm or .html file extension.
These programs look for potential problems in the 'to', 'from' and 'subject' lines, the main body text and attachments by file extension and/or content.
The proposal will result in a common PC file extension for e-book content, ".oeb" (e.g., "fllename.oeb").
* Africa ( The Internet-Drafts on this machine are stored in GNU compressed form (i.e., the .gz file extension).
This media player has a lot of compatibility as it can play sound or video of many file extension types.
With DivX Plus HD Certification, Panasonic UniPhier chips will enable devices to playback a wide variety of video files with the .mkv file extension and AAC audio, whether created with the DivX 7 software or third-party tools.