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

SQL file extension

Structured Query Language Data File

Database Files

ODT file extension

OpenDocument Text Document

Text Files

PKG file extension

Mac OS X Installer Package

Compressed Files

LNK file extension

Windows File Shortcut

System Files

MOV file extension

Apple QuickTime Movie

Video Files

DB file extension

Database File

Database Files

MSI file extension

Windows Installer Package

Misc Files

HTML file extension

Hypertext Markup Language File

Web Files

GZ file extension

Gnu Zipped Archive

Compressed Files

ACCDB file extension

Access 2007 Database File

Database Files

7Z file extension

7-Zip Compressed File

Compressed Files

TIF file extension

Tagged Image File

Raster Image Files

MP4 file extension

MPEG-4 Video File

Video Files

JAR file extension

Java Archive File

Executable Files

MID file extension

MIDI File

Audio Files