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

CPP file extension

C++ Source Code File

Developer Files

CSS file extension

Cascading Style Sheet

Web Files

DTD file extension

Document Type Definition File

Developer Files

DXF file extension

Drawing Exchange Format File

CAD Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

ICS file extension

iCalendar File

Misc Files

MID file extension

MIDI File

Audio Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PDF file extension

Portable Document Format File

Layout Files

PRF file extension

Outlook Profile File

Settings Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

TAR file extension

Consolidated Unix File Archive

Data Files

TXT file extension

Plain Text File

Text Files

VCD file extension

Virtual CD

Disk Image Files