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File extension - what is it?

The file extension is a certain part of the full name of the file. It includes information about the manner and type of data stored in it. This is usually a combination of several characters appearing after the last dot in the file name displayed on screen. Thanks to these characters, we can find out what program supports a given file.

Displaying file extensions

However, file extensions are not always displayed at the file name. Sometimes a computer hides their names. This setting can be edited in the Windows Control Panel, under "Appearance and Personalization" and then "Folder Options".

Common problems with file extensions.

File associationThe most common cause of the problem with opening the file is its incorrect association with the program in the registry. This means that the operating system did not assign to a specific file extension any program that supports it. This setting can easily be edited in the Windows registry.

However, most often there is simply the lack of the appropriate software installed on our device. Then it is sufficient just to download the appropriate program for a given type of the file and install it. You will find the list of programs corresponding to the file extensions on our site FileRegistry.org

Additional advice

If the file has been saved in a format not readable by the dedicated software, in order to open it, one should perform the conversion. For this purpose, a special program should be used that has a converter that easily makes changes to the file format to be read.

.BAK file extension - The full name of the file: Backup File

Programs using this file extension
  • Original program used to create the file
  • Autodesk AutoCAD 2014
  • Microsoft SQL Server 2012

.3DS file extension - The full name of the file: 3D Studio Scene

Programs using this file extension
  • IMSI TurboCAD Deluxe v7
  • Trimble SketchUp
  • Cheetah3D

.KEY file extension - The full name of the file: Keynote Presentation

Programs using this file extension
  • Apple Keynote 5.3
  • Apple Keynote