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

CUR file extension

Windows Cursor

System Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

FNT file extension

Windows Font File

Font Files

GZ file extension

Gnu Zipped Archive

Compressed Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

PCT file extension

Picture File

Layout Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

ROM file extension

N64 Game ROM File

Game Files

RPM file extension

Red Hat Package Manager File

Compressed Files

SYS file extension

Windows System File

System Files

TORRENT file extension

BitTorrent File

Misc Files

WMA file extension

Windows Media Audio File

Audio Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files