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

ASF file extension

Advanced Systems Format File

Video Files

ASX file extension

Microsoft ASF Redirector File

Video Files

CER file extension

Internet Security Certificate

Web Files

CLASS file extension

Java Class File

Developer Files

CUR file extension

Windows Cursor

System Files

DBF file extension

Database File

Database Files

GPX file extension

GPS Exchange File

GIS Files

JAR file extension

Java Archive File

Executable Files

MP3 file extension

MP3 Audio File

Audio Files

PCT file extension

Picture File

Layout Files

TEX file extension

LaTeX Source Document

Text Files

TTF file extension

TrueType Font

Font Files

TXT file extension

Plain Text File

Text Files

WMV file extension

Windows Media Video File

Video Files

3DS file extension

3D Studio Scene

3D Image Files