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

SQL file extension

Structured Query Language Data File

Database Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

VCF file extension

vCard File

Data Files

PNG file extension

Portable Network Graphic

Raster Image Files

M4V file extension

iTunes Video File

Video Files

SLN file extension

Visual Studio Solution File

Developer Files

WAV file extension

WAVE Audio File

Audio Files

CGI file extension

Common Gateway Interface Script

Executable Files

7Z file extension

7-Zip Compressed File

Compressed Files

PHP file extension

PHP Source Code File

Web Files

PRF file extension

Outlook Profile File

Settings Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

ASP file extension

Active Server Page

Web Files

HTM file extension

Hypertext Markup Language File

Web Files

FNT file extension

Windows Font File

Font Files