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

APP file extension

Mac OS X Application

Executable Files

ASPX file extension

Active Server Page Extended File

Web Files

BIN file extension

Binary Disc Image

Disk Image Files

CBR file extension

Comic Book RAR Archive

Compressed Files

DXF file extension

Drawing Exchange Format File

CAD Files

GPX file extension

GPS Exchange File

GIS Files

IFF file extension

Interchange File Format

Audio Files

INI file extension

Windows Initialization File

Settings Files

KEY file extension

Keynote Presentation

Data Files

MP4 file extension

MPEG-4 Video File

Video Files

PHP file extension

PHP Source Code File

Web Files

PL file extension

Perl Script

Developer Files

PNG file extension

Portable Network Graphic

Raster Image Files

SDF file extension

Standard Data File

Data Files

TMP file extension

Temporary File

Backup Files