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

BAT file extension

DOS Batch File

Executable Files

CGI file extension

Common Gateway Interface Script

Executable Files

CSV file extension

Comma Separated Values File

Data Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

FLA file extension

Adobe Flash Animation

Developer Files

GBR file extension

Gerber File

Data Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

IFF file extension

Interchange File Format

Audio Files

MOV file extension

Apple QuickTime Movie

Video Files

OTF file extension

OpenType Font

Font Files

PRF file extension

Outlook Profile File

Settings Files

PY file extension

Python Script

Developer Files

THM file extension

Thumbnail Image File

Raster Image Files

TTF file extension

TrueType Font

Font Files