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

CUR file extension

Windows Cursor

System Files

DEB file extension

Debian Software Package

Compressed Files

DXF file extension

Drawing Exchange Format File

CAD Files

FNT file extension

Windows Font File

Font Files

GED file extension

GEDCOM Genealogy Data File

Data Files

ISO file extension

Disc Image File

Disk Image Files

KEY file extension

Keynote Presentation

Data Files

MSI file extension

Windows Installer Package

Misc Files

PRF file extension

Outlook Profile File

Settings Files

PS file extension

PostScript File

Vector Image Files

THM file extension

Thumbnail Image File

Raster Image Files

TIF file extension

Tagged Image File

Raster Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

TORRENT file extension

BitTorrent File

Misc Files

XLR file extension

Works Spreadsheet

Spreadsheet Files