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

AIF file extension

Audio Interchange File Format

Audio Files

DEB file extension

Debian Software Package

Compressed Files

EPUB file extension

Open eBook File

eBook Files

GZ file extension

Gnu Zipped Archive

Compressed Files

M file extension

Objective-C Implementation File

Developer Files

MOBI file extension

Mobipocket eBook

eBook Files

MOV file extension

Apple QuickTime Movie

Video Files

PAGES file extension

Pages Document

Text Files

SRT file extension

SubRip Subtitle File

Video Files

TARGZ file extension

Compressed Tarball File

Compressed Files

TTF file extension

TrueType Font

Font Files

TXT file extension

Plain Text File

Text Files

VCF file extension

vCard File

Data Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

3DS file extension

3D Studio Scene

3D Image Files