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

CFG file extension

Configuration File

Settings Files

CRX file extension

Chrome Extension

Plugin Files

DBF file extension

Database File

Database Files

DOC# file extension

Microsoft Word Document

Text Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

GED file extension

GEDCOM Genealogy Data File

Data Files

HTM file extension

Hypertext Markup Language File

Web Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

NES file extension

Nintendo (NES) ROM File

Game Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

SQL file extension

Structured Query Language Data File

Database Files

UUE file extension

Uuencoded File

Encoded Files

3DM file extension

Rhino 3D Model

3D Image Files