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

AVI file extension

Audio Video Interleave File

Video Files

CPL file extension

Windows Control Panel Item

System Files

DNG file extension

Digital Negative Image File

Camera Raw Files

DTD file extension

Document Type Definition File

Developer Files

FLV file extension

Flash Video File

Video Files

FON file extension

Generic Font File

Font Files

IFF file extension

Interchange File Format

Audio Files

JAVA file extension

Java Source Code File

Developer Files

M4A file extension

MPEG-4 Audio File

Audio Files

ODT file extension

OpenDocument Text Document

Text Files

PCT file extension

Picture File

Layout Files

PDB file extension

Program Database

Database Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

WSF file extension

Windows Script File

Executable Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files