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

MID file extension

MIDI File

Audio Files

7Z file extension

7-Zip Compressed File

Compressed Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

OTF file extension

OpenType Font

Font Files

GZ file extension

Gnu Zipped Archive

Compressed Files

ODT file extension

OpenDocument Text Document

Text Files

IFF file extension

Interchange File Format

Audio Files

SAV file extension

Saved Game

Game Files

LUA file extension

Lua Source File

Developer Files

MDB file extension

Microsoft Access Database

Database Files

UUE file extension

Uuencoded File

Encoded Files

PART file extension

Partially Downloaded File

Misc Files

MDF file extension

Media Disc Image File

Disk Image Files

BAK file extension

Backup File

Backup Files

LNK file extension

Windows File Shortcut

System Files