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

CS file extension

Visual C# Source Code File

Developer Files

FLA file extension

Adobe Flash Animation

Developer Files

GAM file extension

Saved Game File

Game Files

IBOOKS file extension

Multi-Touch iBook

Data Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

KML file extension

Keyhole Markup Language File

GIS Files

LUA file extension

Lua Source File

Developer Files

MDB file extension

Microsoft Access Database

Database Files

MOV file extension

Apple QuickTime Movie

Video Files

PDB file extension

Program Database

Database Files

SYS file extension

Windows System File

System Files

UUE file extension

Uuencoded File

Encoded Files

WSF file extension

Windows Script File

Executable Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

3G2 file extension

3GPP2 Multimedia File

Video Files