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

DNG file extension

Digital Negative Image File

Camera Raw Files

7Z file extension

7-Zip Compressed File

Compressed Files

RA file extension

Real Audio File

Audio Files

SLN file extension

Visual Studio Solution File

Developer Files

SWF file extension

Shockwave Flash Movie

Video Files

EXE file extension

Windows Executable File

Executable Files

DDS file extension

DirectDraw Surface

Raster Image Files

MOV file extension

Apple QuickTime Movie

Video Files

TXT file extension

Plain Text File

Text Files

MSG file extension

Outlook Mail Message

Text Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

BMP file extension

Bitmap Image File

Raster Image Files

RPM file extension

Red Hat Package Manager File

Compressed Files

AVI file extension

Audio Video Interleave File

Video Files

PY file extension

Python Script

Developer Files