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

AIF file extension

Audio Interchange File Format

Audio Files

CAB file extension

Windows Cabinet File

System Files

CS file extension

Visual C# Source Code File

Developer Files

DMP file extension

Windows Memory Dump

System Files

JAR file extension

Java Archive File

Executable Files

PDB file extension

Program Database

Database Files

PKG file extension

Mac OS X Installer Package

Compressed Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

SH file extension

Bash Shell Script

Developer Files

SWF file extension

Shockwave Flash Movie

Video Files

TAR file extension

Consolidated Unix File Archive

Data Files

THM file extension

Thumbnail Image File

Raster Image Files

ZIPX file extension

Extended Zip File

Compressed Files

3G2 file extension

3GPP2 Multimedia File

Video Files