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

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

SDF file extension

Standard Data File

Data Files

DOC# file extension

Microsoft Word Document

Text Files

CSV file extension

Comma Separated Values File

Data Files

CFG file extension

Configuration File

Settings Files

COM file extension

DOS Command File

Executable Files

TARGZ file extension

Compressed Tarball File

Compressed Files

GADGET file extension

Windows Gadget

Executable Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

DMP file extension

Windows Memory Dump

System Files

MPG file extension

MPEG Video File

Video Files

CER file extension

Internet Security Certificate

Web Files

7Z file extension

7-Zip Compressed File

Compressed Files

LOG file extension

Log File

Text Files