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

CFG file extension

Configuration File

Settings Files

CPL file extension

Windows Control Panel Item

System Files

CUE file extension

Cue Sheet File

Disk Image Files

GED file extension

GEDCOM Genealogy Data File

Data Files

ICNS file extension

Mac OS X Icon Resource File

System Files

JAVA file extension

Java Source Code File

Developer Files

LOG file extension

Log File

Text Files

MDF file extension

Media Disc Image File

Disk Image Files

PART file extension

Partially Downloaded File

Misc Files

PCT file extension

Picture File

Layout Files

PS file extension

PostScript File

Vector Image Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

RA file extension

Real Audio File

Audio Files

TMP file extension

Temporary File

Backup Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files