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

PHP file extension

PHP Source Code File

Web Files

CAB file extension

Windows Cabinet File

System Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

AIF file extension

Audio Interchange File Format

Audio Files

M4A file extension

MPEG-4 Audio File

Audio Files

CPP file extension

C++ Source Code File

Developer Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

ASX file extension

Microsoft ASF Redirector File

Video Files

XCODEPROJ file extension

Xcode Project

Developer Files

PY file extension

Python Script

Developer Files

DDS file extension

DirectDraw Surface

Raster Image Files

VCXPROJ file extension

Visual C++ Project

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files

GZ file extension

Gnu Zipped Archive

Compressed Files

MID file extension

MIDI File

Audio Files