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

BIN file extension

Binary Disc Image

Disk Image Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

GBR file extension

Gerber File

Data Files

GED file extension

GEDCOM Genealogy Data File

Data Files

ISO file extension

Disc Image File

Disk Image Files

KEY file extension

Keynote Presentation

Data Files

MDB file extension

Microsoft Access Database

Database Files

MP4 file extension

MPEG-4 Video File

Video Files

PPT file extension

PowerPoint Presentation

Data Files

PY file extension

Python Script

Developer Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

SLN file extension

Visual Studio Solution File

Developer Files

VCF file extension

vCard File

Data Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

3DM file extension

Rhino 3D Model

3D Image Files