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

CSR file extension

Certificate Signing Request File

Web Files

DAT file extension

Data File

Data Files

DTD file extension

Document Type Definition File

Developer Files

FLV file extension

Flash Video File

Video Files

JAVA file extension

Java Source Code File

Developer Files

MIM file extension

Multi-Purpose Internet Mail Message File

Encoded Files

MPG file extension

MPEG Video File

Video Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SAV file extension

Saved Game

Game Files

TAR file extension

Consolidated Unix File Archive

Data Files

WPS file extension

Microsoft Works Word Processor Document

Text Files

3G2 file extension

3GPP2 Multimedia File

Video Files

3GP file extension

3GPP Multimedia File

Video Files