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

ASP file extension

Active Server Page

Web Files

AZW file extension

Amazon Kindle eBook File

eBook Files

DBF file extension

Database File

Database Files

DRV file extension

Device Driver

System Files

KEY file extension

Keynote Presentation

Data Files

KML file extension

Keyhole Markup Language File

GIS Files

MSG file extension

Outlook Mail Message

Text Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

PY file extension

Python Script

Developer Files

RA file extension

Real Audio File

Audio Files

RSS file extension

Rich Site Summary

Web Files

RTF file extension

Rich Text Format File

Text Files

TOAST file extension

Toast Disc Image

Disk Image Files