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

CSS file extension

Cascading Style Sheet

Web Files

DBF file extension

Database File

Database Files

DEB file extension

Debian Software Package

Compressed Files

DRV file extension

Device Driver

System Files

M4A file extension

MPEG-4 Audio File

Audio Files

RA file extension

Real Audio File

Audio Files

TGA file extension

Targa Graphic

Raster Image Files

THM file extension

Thumbnail Image File

Raster Image Files

VB file extension

VBScript File

Executable Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

3DM file extension

Rhino 3D Model

3D Image Files