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

BAT file extension

DOS Batch File

Executable Files

CAB file extension

Windows Cabinet File

System Files

CSS file extension

Cascading Style Sheet

Web Files

CUE file extension

Cue Sheet File

Disk Image Files

DMP file extension

Windows Memory Dump

System Files

DRV file extension

Device Driver

System Files

ICS file extension

iCalendar File

Misc Files

LUA file extension

Lua Source File

Developer Files

M4V file extension

iTunes Video File

Video Files

MOBI file extension

Mobipocket eBook

eBook Files

SRT file extension

SubRip Subtitle File

Video Files

TAX2012 file extension

TurboTax 2012 Tax Return

Data Files

XML file extension

XML File

Data Files

ZIPX file extension

Extended Zip File

Compressed Files