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

ASP file extension

Active Server Page

Web Files

BIN file extension

Binary Disc Image

Disk Image Files

COM file extension

DOS Command File

Executable Files

CRX file extension

Chrome Extension

Plugin Files

GED file extension

GEDCOM Genealogy Data File

Data Files

ICS file extension

iCalendar File

Misc Files

IFF file extension

Interchange File Format

Audio Files

JS file extension

JavaScript File

Web Files

MDF file extension

Media Disc Image File

Disk Image Files

MOV file extension

Apple QuickTime Movie

Video Files

ODT file extension

OpenDocument Text Document

Text Files

PIF file extension

Program Information File

Executable Files

RTF file extension

Rich Text Format File

Text Files

WAV file extension

WAVE Audio File

Audio Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files