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

APP file extension

Mac OS X Application

Executable Files

CAB file extension

Windows Cabinet File

System Files

CRX file extension

Chrome Extension

Plugin Files

CSR file extension

Certificate Signing Request File

Web Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

GZ file extension

Gnu Zipped Archive

Compressed Files

MOV file extension

Apple QuickTime Movie

Video Files

SH file extension

Bash Shell Script

Developer Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

TIFF file extension

Tagged Image File Format

Raster Image Files

WSF file extension

Windows Script File

Executable Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

3GP file extension

3GPP Multimedia File

Video Files