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

CUR file extension

Windows Cursor

System Files

BAK file extension

Backup File

Backup Files

PY file extension

Python Script

Developer Files

TIF file extension

Tagged Image File

Raster Image Files

PRF file extension

Outlook Profile File

Settings Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

7Z file extension

7-Zip Compressed File

Compressed Files

TMP file extension

Temporary File

Backup Files

MDF file extension

Media Disc Image File

Disk Image Files

KEY file extension

Keynote Presentation

Data Files

MOV file extension

Apple QuickTime Movie

Video Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

GZ file extension

Gnu Zipped Archive

Compressed Files

AVI file extension

Audio Video Interleave File

Video Files

MP3 file extension

MP3 Audio File

Audio Files