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

ACCDB file extension

Access 2007 Database File

Database Files

CER file extension

Internet Security Certificate

Web Files

CUE file extension

Cue Sheet File

Disk Image Files

DNG file extension

Digital Negative Image File

Camera Raw Files

EXE file extension

Windows Executable File

Executable Files

IFF file extension

Interchange File Format

Audio Files

MPA file extension

MPEG-2 Audio File

Audio Files

PIF file extension

Program Information File

Executable Files

PNG file extension

Portable Network Graphic

Raster Image Files

RM file extension

Real Media File

Video Files

SITX file extension

StuffIt X Archive

Compressed Files

TAR file extension

Consolidated Unix File Archive

Data Files

THM file extension

Thumbnail Image File

Raster Image Files

WMV file extension

Windows Media Video File

Video Files

WSF file extension

Windows Script File

Executable Files