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

BAK file extension

Backup File

Backup Files

BMP file extension

Bitmap Image File

Raster Image Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CRX file extension

Chrome Extension

Plugin Files

DMP file extension

Windows Memory Dump

System Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DOC file extension

Microsoft Word Document

Text Files

M4A file extension

MPEG-4 Audio File

Audio Files

PART file extension

Partially Downloaded File

Misc Files

PNG file extension

Portable Network Graphic

Raster Image Files

PRF file extension

Outlook Profile File

Settings Files

SITX file extension

StuffIt X Archive

Compressed Files

SRT file extension

SubRip Subtitle File

Video Files

TEX file extension

LaTeX Source Document

Text Files

TORRENT file extension

BitTorrent File

Misc Files