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

CPL file extension

Windows Control Panel Item

System Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

FON file extension

Generic Font File

Font Files

GBR file extension

Gerber File

Data Files

ICNS file extension

Mac OS X Icon Resource File

System Files

INDD file extension

Adobe InDesign Document

Layout Files

JAR file extension

Java Archive File

Executable Files

LOG file extension

Log File

Text Files

M4V file extension

iTunes Video File

Video Files

SDF file extension

Standard Data File

Data Files

SH file extension

Bash Shell Script

Developer Files

TEX file extension

LaTeX Source Document

Text Files

WAV file extension

WAVE Audio File

Audio Files

ZIP file extension

Zipped File

Compressed Files

3G2 file extension

3GPP2 Multimedia File

Video Files