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

CFG file extension

Configuration File

Settings Files

CPL file extension

Windows Control Panel Item

System Files

CUE file extension

Cue Sheet File

Disk Image Files

DTD file extension

Document Type Definition File

Developer Files

DXF file extension

Drawing Exchange Format File

CAD Files

GAM file extension

Saved Game File

Game Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

JAR file extension

Java Archive File

Executable Files

MP4 file extension

MPEG-4 Video File

Video Files

PDF file extension

Portable Document Format File

Layout Files

SDF file extension

Standard Data File

Data Files

SQL file extension

Structured Query Language Data File

Database Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files