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

ASX file extension

Microsoft ASF Redirector File

Video Files

BMP file extension

Bitmap Image File

Raster Image Files

CBR file extension

Comic Book RAR Archive

Compressed Files

CSV file extension

Comma Separated Values File

Data Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

ICS file extension

iCalendar File

Misc Files

LOG file extension

Log File

Text Files

MID file extension

MIDI File

Audio Files

PCT file extension

Picture File

Layout Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PPS file extension

PowerPoint Slide Show

Data Files

RTF file extension

Rich Text Format File

Text Files

SQL file extension

Structured Query Language Data File

Database Files

VCD file extension

Virtual CD

Disk Image Files

WSF file extension

Windows Script File

Executable Files