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

BIN file extension

Binary Disc Image

Disk Image Files

CFG file extension

Configuration File

Settings Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CS file extension

Visual C# Source Code File

Developer Files

DAT file extension

Data File

Data Files

DLL file extension

Dynamic Link Library

System Files

FON file extension

Generic Font File

Font Files

ISO file extension

Disc Image File

Disk Image Files

JPG file extension

JPEG Image

Raster Image Files

PKG file extension

Mac OS X Installer Package

Compressed Files

WAV file extension

WAVE Audio File

Audio Files

WMV file extension

Windows Media Video File

Video Files

XCODEPROJ file extension

Xcode Project

Developer Files

YUV file extension

YUV Encoded Image File

Raster Image Files