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

ACCDB file extension

Access 2007 Database File

Database Files

CER file extension

Internet Security Certificate

Web Files

CSV file extension

Comma Separated Values File

Data Files

DDS file extension

DirectDraw Surface

Raster Image Files

DNG file extension

Digital Negative Image File

Camera Raw Files

JPG file extension

JPEG Image

Raster Image Files

KML file extension

Keyhole Markup Language File

GIS Files

MP4 file extension

MPEG-4 Video File

Video Files

PDB file extension

Program Database

Database Files

RTF file extension

Rich Text Format File

Text Files

TTF file extension

TrueType Font

Font Files

WMA file extension

Windows Media Audio File

Audio Files

WMV file extension

Windows Media Video File

Video Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

XLR file extension

Works Spreadsheet

Spreadsheet Files