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The File Extension Library

What is a file extension?

Short answer: it's the set of letters after the period (.) in the name of a file.

Long answer: File extensions signify the file format of a file. It tells the operating system (OS) how data was stored in the file. Not all OS, require a file extension though. For instance, this is optional in Unix, but is mandatory with MS-DOS and Windows systems.

In most file formats the file type is actually defined by the contents (first bytes, file structure), but extensions are used to define the application that is used for opening the file.

Below is a detailed database of thousands of file extensions our team has compiled for you. Feel free to browse!


Browse all Extensions:
ABCDEFGHIJKLMNOPQRSTUVWXYZ
ICO - Extension Details
Date Added: January 01, 1970
File Extension:  .ICO
Description 1: .ICO file extension is linked with Icon File. It is the image file format that is used by Windows programs, files and folders in storing icons. It has two bitmaps: AND bitmap which is the image mask that determines the transparent part of the icon, and XOR bitmap which carries the icon that is mapped on to the image mask. An .ICO file is comparable to Windows cursor [.CUR] file but it has a different classification byte in the header.
File Type:   Bitmap Image File
Mode: Binary
Program(s) to Open:  Windows: ACDSee Photo Manager, Adobe Photoshop, IconEdit2, IvanView, Program4Pc PC Icon Editor; Mac: Adobe Photoshop, Lemkesoft GraphicConverter, Newera Software InconCool Editor
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