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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
KEYNOTE - Extension Details
Date Added: January 11, 2008
File Extension:  .KEYNOTE
Description 1: .KEYNOTE file extension is linked with Keynote Presentations. Keynote is a presentation program developed as a part of iWork Productivity Suite by Apple Inc. This application was released in 2007 and the latest version, Keynote 4, runs on Mac OS X 10.4 Tiger and 10.5 Leopard. .KEYNOTE file extension and Keynote are owned and developed by Apple Inc.
File Type:   Document File
Mode: Binary
Program(s) to Open:  Mac: Keynote
Common:
Extension: