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

LNK file extension

Windows File Shortcut

System Files

PCT file extension

Picture File

Layout Files

MAX file extension

3ds Max Scene File

3D Image Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

TIFF file extension

Tagged Image File Format

Raster Image Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

DBF file extension

Database File

Database Files

7Z file extension

7-Zip Compressed File

Compressed Files

CER file extension

Internet Security Certificate

Web Files

C file extension

C/C++ Source Code File

Developer Files

KML file extension

Keyhole Markup Language File

GIS Files

WAV file extension

WAVE Audio File

Audio Files

COM file extension

DOS Command File

Executable Files

ICO file extension

Icon File

System Files

ASF file extension

Advanced Systems Format File

Video Files