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

CGI file extension

Common Gateway Interface Script

Executable Files

CLASS file extension

Java Class File

Developer Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CSR file extension

Certificate Signing Request File

Web Files

DNG file extension

Digital Negative Image File

Camera Raw Files

JAR file extension

Java Archive File

Executable Files

LNK file extension

Windows File Shortcut

System Files

M4A file extension

MPEG-4 Audio File

Audio Files

MOV file extension

Apple QuickTime Movie

Video Files

PY file extension

Python Script

Developer Files

VCF file extension

vCard File

Data Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

WSF file extension

Windows Script File

Executable Files

3DS file extension

3D Studio Scene

3D Image Files

3GP file extension

3GPP Multimedia File

Video Files