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

MAX file extension

3ds Max Scene File

3D Image Files

BAK file extension

Backup File

Backup Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

3DM file extension

Rhino 3D Model

3D Image Files

LOG file extension

Log File

Text Files

CER file extension

Internet Security Certificate

Web Files

CUE file extension

Cue Sheet File

Disk Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

SQL file extension

Structured Query Language Data File

Database Files

PPS file extension

PowerPoint Slide Show

Data Files

VB file extension

VBScript File

Executable Files

SYS file extension

Windows System File

System Files

7Z file extension

7-Zip Compressed File

Compressed Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

DOCX file extension

Microsoft Word Open XML Document

Text Files