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

DOC file extension

Microsoft Word Document

Text Files

IFF file extension

Interchange File Format

Audio Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

7Z file extension

7-Zip Compressed File

Compressed Files

PPT file extension

PowerPoint Presentation

Data Files

NES file extension

Nintendo (NES) ROM File

Game Files

XLS file extension

Excel Spreadsheet

Spreadsheet Files

M4V file extension

iTunes Video File

Video Files

ICS file extension

iCalendar File

Misc Files

SAV file extension

Saved Game

Game Files

CAB file extension

Windows Cabinet File

System Files

LOG file extension

Log File

Text Files

TMP file extension

Temporary File

Backup Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

AVI file extension

Audio Video Interleave File

Video Files