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

ASPX file extension

Active Server Page Extended File

Web Files

CER file extension

Internet Security Certificate

Web Files

EXE file extension

Windows Executable File

Executable Files

INI file extension

Windows Initialization File

Settings Files

JSP file extension

Java Server Page

Web Files

LNK file extension

Windows File Shortcut

System Files

M4V file extension

iTunes Video File

Video Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MOBI file extension

Mobipocket eBook

eBook Files

MPG file extension

MPEG Video File

Video Files

TGA file extension

Targa Graphic

Raster Image Files

TORRENT file extension

BitTorrent File

Misc Files

YUV file extension

YUV Encoded Image File

Raster Image Files

ZIPX file extension

Extended Zip File

Compressed Files

3DM file extension

Rhino 3D Model

3D Image Files