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

TMP file extension

Temporary File

Backup Files

EXE file extension

Windows Executable File

Executable Files

PKG file extension

Mac OS X Installer Package

Compressed Files

DOC# file extension

Microsoft Word Document

Text Files

PS file extension

PostScript File

Vector Image Files

CBR file extension

Comic Book RAR Archive

Compressed Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

CSR file extension

Certificate Signing Request File

Web Files

7Z file extension

7-Zip Compressed File

Compressed Files

CRX file extension

Chrome Extension

Plugin Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

FLV file extension

Flash Video File

Video Files

KMZ file extension

Google Earth Placemark File

GIS Files

BIN file extension

Binary Disc Image

Disk Image Files

VCD file extension

Virtual CD

Disk Image Files