File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

CBR file extension

Comic Book RAR Archive

Compressed Files

DMP file extension

Windows Memory Dump

System Files

DXF file extension

Drawing Exchange Format File

CAD Files

IBOOKS file extension

Multi-Touch iBook

Data Files

ICNS file extension

Mac OS X Icon Resource File

System Files

MPG file extension

MPEG Video File

Video Files

MSI file extension

Windows Installer Package

Misc Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

THM file extension

Thumbnail Image File

Raster Image Files

VOB file extension

DVD Video Object File

Video Files

WAV file extension

WAVE Audio File

Audio Files

WMV file extension

Windows Media Video File

Video Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

XML file extension

XML File

Data Files

3DS file extension

3D Studio Scene

3D Image Files