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

AI file extension

Adobe Illustrator File

Vector Image Files

AIF file extension

Audio Interchange File Format

Audio Files

ASF file extension

Advanced Systems Format File

Video Files

CGI file extension

Common Gateway Interface Script

Executable Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CSR file extension

Certificate Signing Request File

Web Files

CUE file extension

Cue Sheet File

Disk Image Files

DLL file extension

Dynamic Link Library

System Files

DNG file extension

Digital Negative Image File

Camera Raw Files

INI file extension

Windows Initialization File

Settings Files

LNK file extension

Windows File Shortcut

System Files

ODT file extension

OpenDocument Text Document

Text Files

PNG file extension

Portable Network Graphic

Raster Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

XCODEPROJ file extension

Xcode Project

Developer Files