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

CFG file extension

Configuration File

Settings Files

CS file extension

Visual C# Source Code File

Developer Files

CSS file extension

Cascading Style Sheet

Web Files

DAT file extension

Data File

Data Files

DBF file extension

Database File

Database Files

DXF file extension

Drawing Exchange Format File

CAD Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

LOG file extension

Log File

Text Files

M3U file extension

Media Playlist File

Audio Files

MAX file extension

3ds Max Scene File

3D Image Files

PDB file extension

Program Database

Database Files

PIF file extension

Program Information File

Executable Files

PKG file extension

Mac OS X Installer Package

Compressed Files

TGA file extension

Targa Graphic

Raster Image Files

TMP file extension

Temporary File

Backup Files