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

APK file extension

Android Package File

Executable Files

CSS file extension

Cascading Style Sheet

Web Files

DBF file extension

Database File

Database Files

DDS file extension

DirectDraw Surface

Raster Image Files

DOC# file extension

Microsoft Word Document

Text Files

H file extension

C/C++/Objective-C Header File

Developer Files

KMZ file extension

Google Earth Placemark File

GIS Files

M4V file extension

iTunes Video File

Video Files

MOBI file extension

Mobipocket eBook

eBook Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

ODT file extension

OpenDocument Text Document

Text Files

TGA file extension

Targa Graphic

Raster Image Files

TMP file extension

Temporary File

Backup Files

TXT file extension

Plain Text File

Text Files

ZIP file extension

Zipped File

Compressed Files