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

BIN file extension

Binary Disc Image

Disk Image Files

CGI file extension

Common Gateway Interface Script

Executable Files

DOC file extension

Microsoft Word Document

Text Files

EPUB file extension

Open eBook File

eBook Files

GED file extension

GEDCOM Genealogy Data File

Data Files

ICNS file extension

Mac OS X Icon Resource File

System Files

ODT file extension

OpenDocument Text Document

Text Files

PL file extension

Perl Script

Developer Files

PPT file extension

PowerPoint Presentation

Data Files

RSS file extension

Rich Site Summary

Web Files

SAV file extension

Saved Game

Game Files

SH file extension

Bash Shell Script

Developer Files

TOAST file extension

Toast Disc Image

Disk Image Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

XML file extension

XML File

Data Files