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

MPG file extension

MPEG Video File

Video Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

ICS file extension

iCalendar File

Misc Files

TEX file extension

LaTeX Source Document

Text Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

HTML file extension

Hypertext Markup Language File

Web Files

KML file extension

Keyhole Markup Language File

GIS Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

GED file extension

GEDCOM Genealogy Data File

Data Files

CUR file extension

Windows Cursor

System Files

C file extension

C/C++ Source Code File

Developer Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

7Z file extension

7-Zip Compressed File

Compressed Files