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

INI file extension

Windows Initialization File

Settings Files

DBF file extension

Database File

Database Files

PS file extension

PostScript File

Vector Image Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

TEX file extension

LaTeX Source Document

Text Files

MOBI file extension

Mobipocket eBook

eBook Files

WPD file extension

WordPerfect Document

Text Files

DAT file extension

Data File

Data Files

JAR file extension

Java Archive File

Executable Files

SAV file extension

Saved Game

Game Files

KML file extension

Keyhole Markup Language File

GIS Files

3DS file extension

3D Studio Scene

3D Image Files

7Z file extension

7-Zip Compressed File

Compressed Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

RTF file extension

Rich Text Format File

Text Files