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

APK file extension

Android Package File

Executable Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

DDS file extension

DirectDraw Surface

Raster Image Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

ICNS file extension

Mac OS X Icon Resource File

System Files

PIF file extension

Program Information File

Executable Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

RA file extension

Real Audio File

Audio Files

RPM file extension

Red Hat Package Manager File

Compressed Files

RTF file extension

Rich Text Format File

Text Files

THM file extension

Thumbnail Image File

Raster Image Files

TOAST file extension

Toast Disc Image

Disk Image Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files