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

7Z file extension

7-Zip Compressed File

Compressed Files

MP3 file extension

MP3 Audio File

Audio Files

CAB file extension

Windows Cabinet File

System Files

VCF file extension

vCard File

Data Files

GZ file extension

Gnu Zipped Archive

Compressed Files

CSR file extension

Certificate Signing Request File

Web Files

PNG file extension

Portable Network Graphic

Raster Image Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

PKG file extension

Mac OS X Installer Package

Compressed Files

VB file extension

VBScript File

Executable Files

TGA file extension

Targa Graphic

Raster Image Files

SDF file extension

Standard Data File

Data Files

PCT file extension

Picture File

Layout Files

ASF file extension

Advanced Systems Format File

Video Files

DOC file extension

Microsoft Word Document

Text Files