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

LOG file extension

Log File

Text Files

CFG file extension

Configuration File

Settings Files

RM file extension

Real Media File

Video Files

PART file extension

Partially Downloaded File

Misc Files

WPD file extension

WordPerfect Document

Text Files

APP file extension

Mac OS X Application

Executable Files

JAR file extension

Java Archive File

Executable Files

TORRENT file extension

BitTorrent File

Misc Files

HTML file extension

Hypertext Markup Language File

Web Files

ICO file extension

Icon File

System Files

CRX file extension

Chrome Extension

Plugin Files

7Z file extension

7-Zip Compressed File

Compressed Files

ICNS file extension

Mac OS X Icon Resource File

System Files

TIF file extension

Tagged Image File

Raster Image Files

PAGES file extension

Pages Document

Text Files