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

TMP file extension

Temporary File

Backup Files

3GP file extension

3GPP Multimedia File

Video Files

WMV file extension

Windows Media Video File

Video Files

TIFF file extension

Tagged Image File Format

Raster Image Files

WMA file extension

Windows Media Audio File

Audio Files

BMP file extension

Bitmap Image File

Raster Image Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

7Z file extension

7-Zip Compressed File

Compressed Files

KMZ file extension

Google Earth Placemark File

GIS Files

ODT file extension

OpenDocument Text Document

Text Files

3DM file extension

Rhino 3D Model

3D Image Files

DLL file extension

Dynamic Link Library

System Files

MDF file extension

Media Disc Image File

Disk Image Files

CUR file extension

Windows Cursor

System Files

BIN file extension

Binary Disc Image

Disk Image Files