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

ACCDB file extension

Access 2007 Database File

Database Files

ASPX file extension

Active Server Page Extended File

Web Files

DOC file extension

Microsoft Word Document

Text Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

FNT file extension

Windows Font File

Font Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

IFF file extension

Interchange File Format

Audio Files

M4V file extension

iTunes Video File

Video Files

MOBI file extension

Mobipocket eBook

eBook Files

NES file extension

Nintendo (NES) ROM File

Game Files

PNG file extension

Portable Network Graphic

Raster Image Files

PS file extension

PostScript File

Vector Image Files

SH file extension

Bash Shell Script

Developer Files

TXT file extension

Plain Text File

Text Files

WAV file extension

WAVE Audio File

Audio Files