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

COM file extension

DOS Command File

Executable Files

GZ file extension

Gnu Zipped Archive

Compressed Files

GED file extension

GEDCOM Genealogy Data File

Data Files

VB file extension

VBScript File

Executable Files

CPL file extension

Windows Control Panel Item

System Files

AI file extension

Adobe Illustrator File

Vector Image Files

ACCDB file extension

Access 2007 Database File

Database Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

IBOOKS file extension

Multi-Touch iBook

Data Files

DLL file extension

Dynamic Link Library

System Files

JAR file extension

Java Archive File

Executable Files

7Z file extension

7-Zip Compressed File

Compressed Files

DRV file extension

Device Driver

System Files

UUE file extension

Uuencoded File

Encoded Files

KMZ file extension

Google Earth Placemark File

GIS Files