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

BAK file extension

Backup File

Backup Files

FNT file extension

Windows Font File

Font Files

MP4 file extension

MPEG-4 Video File

Video Files

MOV file extension

Apple QuickTime Movie

Video Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

VB file extension

VBScript File

Executable Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

APK file extension

Android Package File

Executable Files

RTF file extension

Rich Text Format File

Text Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

CSV file extension

Comma Separated Values File

Data Files

DAT file extension

Data File

Data Files

XML file extension

XML File

Data Files

7Z file extension

7-Zip Compressed File

Compressed Files

MAX file extension

3ds Max Scene File

3D Image Files