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

ASP file extension

Active Server Page

Web Files

CGI file extension

Common Gateway Interface Script

Executable Files

DAT file extension

Data File

Data Files

DDS file extension

DirectDraw Surface

Raster Image Files

DOC file extension

Microsoft Word Document

Text Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

DXF file extension

Drawing Exchange Format File

CAD Files

EPS file extension

Encapsulated PostScript File

Vector Image Files

JAR file extension

Java Archive File

Executable Files

LOG file extension

Log File

Text Files

PDB file extension

Program Database

Database Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

PY file extension

Python Script

Developer Files

TEX file extension

LaTeX Source Document

Text Files

WPS file extension

Microsoft Works Word Processor Document

Text Files