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

CAB file extension

Windows Cabinet File

System Files

CRX file extension

Chrome Extension

Plugin Files

DAT file extension

Data File

Data Files

EPUB file extension

Open eBook File

eBook Files

INDD file extension

Adobe InDesign Document

Layout Files

JSP file extension

Java Server Page

Web Files

M4V file extension

iTunes Video File

Video Files

MPA file extension

MPEG-2 Audio File

Audio Files

PDB file extension

Program Database

Database Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PPS file extension

PowerPoint Slide Show

Data Files

RTF file extension

Rich Text Format File

Text Files

SH file extension

Bash Shell Script

Developer Files

TORRENT file extension

BitTorrent File

Misc Files