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

7Z file extension

7-Zip Compressed File

Compressed Files

PL file extension

Perl Script

Developer Files

SLN file extension

Visual Studio Solution File

Developer Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

YUV file extension

YUV Encoded Image File

Raster Image Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

RTF file extension

Rich Text Format File

Text Files

CS file extension

Visual C# Source Code File

Developer Files

DEB file extension

Debian Software Package

Compressed Files

TIF file extension

Tagged Image File

Raster Image Files

CGI file extension

Common Gateway Interface Script

Executable Files

JAR file extension

Java Archive File

Executable Files

3DS file extension

3D Studio Scene

3D Image Files

M4A file extension

MPEG-4 Audio File

Audio Files

GED file extension

GEDCOM Genealogy Data File

Data Files