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

AIF file extension

Audio Interchange File Format

Audio Files

ASX file extension

Microsoft ASF Redirector File

Video Files

CSR file extension

Certificate Signing Request File

Web Files

CSV file extension

Comma Separated Values File

Data Files

EPUB file extension

Open eBook File

eBook Files

GZ file extension

Gnu Zipped Archive

Compressed Files

JAR file extension

Java Archive File

Executable Files

KML file extension

Keyhole Markup Language File

GIS Files

M file extension

Objective-C Implementation File

Developer Files

M4A file extension

MPEG-4 Audio File

Audio Files

PIF file extension

Program Information File

Executable Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

WMV file extension

Windows Media Video File

Video Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

ZIPX file extension

Extended Zip File

Compressed Files