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

ROM file extension

N64 Game ROM File

Game Files

INI file extension

Windows Initialization File

Settings Files

7Z file extension

7-Zip Compressed File

Compressed Files

BAT file extension

DOS Batch File

Executable Files

CPL file extension

Windows Control Panel Item

System Files

TMP file extension

Temporary File

Backup Files

WMV file extension

Windows Media Video File

Video Files

DEM file extension

Video Game Demo File

Game Files

PART file extension

Partially Downloaded File

Misc Files

CLASS file extension

Java Class File

Developer Files

PDF file extension

Portable Document Format File

Layout Files

CSV file extension

Comma Separated Values File

Data Files

TORRENT file extension

BitTorrent File

Misc Files

ICS file extension

iCalendar File

Misc Files

MOBI file extension

Mobipocket eBook

eBook Files