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

ASPX file extension

Active Server Page Extended File

Web Files

COM file extension

DOS Command File

Executable Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CSV file extension

Comma Separated Values File

Data Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

ICNS file extension

Mac OS X Icon Resource File

System Files

JS file extension

JavaScript File

Web Files

LOG file extension

Log File

Text Files

MID file extension

MIDI File

Audio Files

MSG file extension

Outlook Mail Message

Text Files

PNG file extension

Portable Network Graphic

Raster Image Files

RM file extension

Real Media File

Video Files

TGA file extension

Targa Graphic

Raster Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

3GP file extension

3GPP Multimedia File

Video Files