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

BIN file extension

Binary Disc Image

Disk Image Files

CLASS file extension

Java Class File

Developer Files

DAT file extension

Data File

Data Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

GPX file extension

GPS Exchange File

GIS Files

JS file extension

JavaScript File

Web Files

MP4 file extension

MPEG-4 Video File

Video Files

MSI file extension

Windows Installer Package

Misc Files

NES file extension

Nintendo (NES) ROM File

Game Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

SYS file extension

Windows System File

System Files

TMP file extension

Temporary File

Backup Files

VCXPROJ file extension

Visual C++ Project

Developer Files

XCODEPROJ file extension

Xcode Project

Developer Files

3GP file extension

3GPP Multimedia File

Video Files