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

7Z file extension

7-Zip Compressed File

Compressed Files

CLASS file extension

Java Class File

Developer Files

JPG file extension

JPEG Image

Raster Image Files

ASX file extension

Microsoft ASF Redirector File

Video Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

RA file extension

Real Audio File

Audio Files

OTF file extension

OpenType Font

Font Files

FLA file extension

Adobe Flash Animation

Developer Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PRF file extension

Outlook Profile File

Settings Files

PDF file extension

Portable Document Format File

Layout Files

MP3 file extension

MP3 Audio File

Audio Files

3DM file extension

Rhino 3D Model

3D Image Files

TARGZ file extension

Compressed Tarball File

Compressed Files

JAR file extension

Java Archive File

Executable Files