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

3DM file extension

Rhino 3D Model

3D Image Files

ZIP file extension

Zipped File

Compressed Files

CPP file extension

C++ Source Code File

Developer Files

CS file extension

Visual C# Source Code File

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files

PNG file extension

Portable Network Graphic

Raster Image Files

SQL file extension

Structured Query Language Data File

Database Files

LOG file extension

Log File

Text Files

M4A file extension

MPEG-4 Audio File

Audio Files

ASF file extension

Advanced Systems Format File

Video Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

DRV file extension

Device Driver

System Files

DTD file extension

Document Type Definition File

Developer Files

MPA file extension

MPEG-2 Audio File

Audio Files

ASP file extension

Active Server Page

Web Files