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

DWG file extension

AutoCAD Drawing Database File

CAD Files

FLA file extension

Adobe Flash Animation

Developer Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

INDD file extension

Adobe InDesign Document

Layout Files

JAVA file extension

Java Source Code File

Developer Files

M4V file extension

iTunes Video File

Video Files

OTF file extension

OpenType Font

Font Files

PDB file extension

Program Database

Database Files

PDF file extension

Portable Document Format File

Layout Files

PPS file extension

PowerPoint Slide Show

Data Files

RSS file extension

Rich Site Summary

Web Files

RTF file extension

Rich Text Format File

Text Files

SDF file extension

Standard Data File

Data Files

SH file extension

Bash Shell Script

Developer Files

SWF file extension

Shockwave Flash Movie

Video Files