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

ASX file extension

Microsoft ASF Redirector File

Video Files

BAT file extension

DOS Batch File

Executable Files

CSR file extension

Certificate Signing Request File

Web Files

DEM file extension

Video Game Demo File

Game Files

DLL file extension

Dynamic Link Library

System Files

DOC# file extension

Microsoft Word Document

Text Files

DXF file extension

Drawing Exchange Format File

CAD Files

MPA file extension

MPEG-2 Audio File

Audio Files

ODT file extension

OpenDocument Text Document

Text Files

PDB file extension

Program Database

Database Files

PDF file extension

Portable Document Format File

Layout Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

SAV file extension

Saved Game

Game Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files