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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
H1T - Extension Details
Date Added: January 01, 1970
File Extension:  .H1T
Description 1: .H1T file extension is linked with Microsoft Windows Assistance Platform Client Help Related File. It is parallel to MS Help 2.x.HxT file. .H1T file defines the organization and content of TOC [table of contents] for a collection. The .H1T files define the TOC for all OEM and Corporate namespace contents. The Assistance Platform can be customized via system builders, OEMs and enterprise clients under license agreement; third parties are not authorized.
File Type:   System File
Mode: Binary
Program(s) to Open:  Windows Vista: HelpPane.exe [for Assistance Platform]
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