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

3G2 file extension

3GPP2 Multimedia File

Video Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

INI file extension

Windows Initialization File

Settings Files

CFM file extension

ColdFusion Markup File

Web Files

CSR file extension

Certificate Signing Request File

Web Files

PRF file extension

Outlook Profile File

Settings Files

7Z file extension

7-Zip Compressed File

Compressed Files

H file extension

C/C++/Objective-C Header File

Developer Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

TIFF file extension

Tagged Image File Format

Raster Image Files

FNT file extension

Windows Font File

Font Files

TAR file extension

Consolidated Unix File Archive

Data Files

DLL file extension

Dynamic Link Library

System Files

PPT file extension

PowerPoint Presentation

Data Files

HTM file extension

Hypertext Markup Language File

Web Files