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

ACCDB file extension

Access 2007 Database File

Database Files

DB file extension

Database File

Database Files

IBOOKS file extension

Multi-Touch iBook

Data Files

ICO file extension

Icon File

System Files

ISO file extension

Disc Image File

Disk Image Files

JAR file extension

Java Archive File

Executable Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

M4A file extension

MPEG-4 Audio File

Audio Files

MPA file extension

MPEG-2 Audio File

Audio Files

PNG file extension

Portable Network Graphic

Raster Image Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

TARGZ file extension

Compressed Tarball File

Compressed Files

VCD file extension

Virtual CD

Disk Image Files

WMV file extension

Windows Media Video File

Video Files

WPD file extension

WordPerfect Document

Text Files