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

CLASS file extension

Java Class File

Developer Files

PPS file extension

PowerPoint Slide Show

Data Files

TORRENT file extension

BitTorrent File

Misc Files

TIF file extension

Tagged Image File

Raster Image Files

JAVA file extension

Java Source Code File

Developer Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

IFF file extension

Interchange File Format

Audio Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DDS file extension

DirectDraw Surface

Raster Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

VCXPROJ file extension

Visual C++ Project

Developer Files

PDF file extension

Portable Document Format File

Layout Files

AVI file extension

Audio Video Interleave File

Video Files

KEY file extension

Keynote Presentation

Data Files

MPG file extension

MPEG Video File

Video Files