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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
QTI - Extension Details
Date Added: January 01, 1970
File Extension:  .QTI
Description 1: .QTI is the file extension used for QuickTime Image files. It is associated with images that are created and compressed via the Apple QuickTime application. QuickTime movies and QTI files have something in common: they both use the same atom types the "idat, containing the image data; and the "idsc which includes the image description. For QuickTime images, Apple encourages using the .QIF file extension.
File Type:   Image file
Mode: Binary
Program(s) to Open:  Mac and Windows: Apple QuickTime Player
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