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

CFM file extension

ColdFusion Markup File

Web Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

FLA file extension

Adobe Flash Animation

Developer Files

GBR file extension

Gerber File

Data Files

GPX file extension

GPS Exchange File

GIS Files

MAX file extension

3ds Max Scene File

3D Image Files

MDF file extension

Media Disc Image File

Disk Image Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

PY file extension

Python Script

Developer Files

VCD file extension

Virtual CD

Disk Image Files

VCF file extension

vCard File

Data Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

3G2 file extension

3GPP2 Multimedia File

Video Files