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

MPA file extension

MPEG-2 Audio File

Audio Files

MID file extension

MIDI File

Audio Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

JAVA file extension

Java Source Code File

Developer Files

PDF file extension

Portable Document Format File

Layout Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

MDF file extension

Media Disc Image File

Disk Image Files

OTF file extension

OpenType Font

Font Files

SYS file extension

Windows System File

System Files

PPS file extension

PowerPoint Slide Show

Data Files

COM file extension

DOS Command File

Executable Files

TOAST file extension

Toast Disc Image

Disk Image Files