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

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

ISO file extension

Disc Image File

Disk Image Files

M4V file extension

iTunes Video File

Video Files

MID file extension

MIDI File

Audio Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MP3 file extension

MP3 Audio File

Audio Files

MP4 file extension

MPEG-4 Video File

Video Files

OTF file extension

OpenType Font

Font Files

PS file extension

PostScript File

Vector Image Files

RA file extension

Real Audio File

Audio Files

SQL file extension

Structured Query Language Data File

Database Files

TMP file extension

Temporary File

Backup Files

TOAST file extension

Toast Disc Image

Disk Image Files

3DM file extension

Rhino 3D Model

3D Image Files