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

MP4 file extension

MPEG-4 Video File

Video Files

NES file extension

Nintendo (NES) ROM File

Game Files

PY file extension

Python Script

Developer Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

JAR file extension

Java Archive File

Executable Files

ICO file extension

Icon File

System Files

CFG file extension

Configuration File

Settings Files

DRV file extension

Device Driver

System Files

7Z file extension

7-Zip Compressed File

Compressed Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

IBOOKS file extension

Multi-Touch iBook

Data Files

EXE file extension

Windows Executable File

Executable Files

MSI file extension

Windows Installer Package

Misc Files

BMP file extension

Bitmap Image File

Raster Image Files

WMV file extension

Windows Media Video File

Video Files