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

VOB file extension

DVD Video Object File

Video Files

DBF file extension

Database File

Database Files

ASPX file extension

Active Server Page Extended File

Web Files

CSR file extension

Certificate Signing Request File

Web Files

TEX file extension

LaTeX Source Document

Text Files

PHP file extension

PHP Source Code File

Web Files

CUE file extension

Cue Sheet File

Disk Image Files

CPP file extension

C++ Source Code File

Developer Files

MP3 file extension

MP3 Audio File

Audio Files

TIFF file extension

Tagged Image File Format

Raster Image Files

DXF file extension

Drawing Exchange Format File

CAD Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

7Z file extension

7-Zip Compressed File

Compressed Files

TOAST file extension

Toast Disc Image

Disk Image Files

INDD file extension

Adobe InDesign Document

Layout Files