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

ASP file extension

Active Server Page

Web Files

CAB file extension

Windows Cabinet File

System Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CUE file extension

Cue Sheet File

Disk Image Files

DRV file extension

Device Driver

System Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

PART file extension

Partially Downloaded File

Misc Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PRF file extension

Outlook Profile File

Settings Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

ROM file extension

N64 Game ROM File

Game Files

RTF file extension

Rich Text Format File

Text Files

TOAST file extension

Toast Disc Image

Disk Image Files

YUV file extension

YUV Encoded Image File

Raster Image Files