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

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

VCF file extension

vCard File

Data Files

ICNS file extension

Mac OS X Icon Resource File

System Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

WPD file extension

WordPerfect Document

Text Files

H file extension

C/C++/Objective-C Header File

Developer Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

BAT file extension

DOS Batch File

Executable Files

RTF file extension

Rich Text Format File

Text Files

GZ file extension

Gnu Zipped Archive

Compressed Files

CSR file extension

Certificate Signing Request File

Web Files

KMZ file extension

Google Earth Placemark File

GIS Files

3DS file extension

3D Studio Scene

3D Image Files

RA file extension

Real Audio File

Audio Files

7Z file extension

7-Zip Compressed File

Compressed Files