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

GPX file extension

GPS Exchange File

GIS Files

TEX file extension

LaTeX Source Document

Text Files

RA file extension

Real Audio File

Audio Files

OTF file extension

OpenType Font

Font Files

7Z file extension

7-Zip Compressed File

Compressed Files

3DM file extension

Rhino 3D Model

3D Image Files

DBF file extension

Database File

Database Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

COM file extension

DOS Command File

Executable Files

CGI file extension

Common Gateway Interface Script

Executable Files

PCT file extension

Picture File

Layout Files

VCD file extension

Virtual CD

Disk Image Files

MOBI file extension

Mobipocket eBook

eBook Files

AVI file extension

Audio Video Interleave File

Video Files

TOAST file extension

Toast Disc Image

Disk Image Files