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

GBR file extension

Gerber File

Data Files

ASP file extension

Active Server Page

Web Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

XCODEPROJ file extension

Xcode Project

Developer Files

FNT file extension

Windows Font File

Font Files

C file extension

C/C++ Source Code File

Developer Files

PDB file extension

Program Database

Database Files

ZIPX file extension

Extended Zip File

Compressed Files

ASX file extension

Microsoft ASF Redirector File

Video Files

MP3 file extension

MP3 Audio File

Audio Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

CS file extension

Visual C# Source Code File

Developer Files

PART file extension

Partially Downloaded File

Misc Files

7Z file extension

7-Zip Compressed File

Compressed Files

DTD file extension

Document Type Definition File

Developer Files