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

DB file extension

Database File

Database Files

CUR file extension

Windows Cursor

System Files

IFF file extension

Interchange File Format

Audio Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

NES file extension

Nintendo (NES) ROM File

Game Files

PLUGIN file extension

Mac OS X Plug-in

Plugin Files

3GP file extension

3GPP Multimedia File

Video Files

PS file extension

PostScript File

Vector Image Files

DRV file extension

Device Driver

System Files

AZW file extension

Amazon Kindle eBook File

eBook Files

DMG file extension

Mac OS X Disk Image

Disk Image Files

TMP file extension

Temporary File

Backup Files

7Z file extension

7-Zip Compressed File

Compressed Files

APK file extension

Android Package File

Executable Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files