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

BIN file extension

Binary Disc Image

Disk Image Files

CUE file extension

Cue Sheet File

Disk Image Files

CUR file extension

Windows Cursor

System Files

DEB file extension

Debian Software Package

Compressed Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DOC file extension

Microsoft Word Document

Text Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

GADGET file extension

Windows Gadget

Executable Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

IFF file extension

Interchange File Format

Audio Files

MP4 file extension

MPEG-4 Video File

Video Files

MSG file extension

Outlook Mail Message

Text Files

TTF file extension

TrueType Font

Font Files

VCF file extension

vCard File

Data Files

3G2 file extension

3GPP2 Multimedia File

Video Files