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

CLASS file extension

Java Class File

Developer Files

DMP file extension

Windows Memory Dump

System Files

DRV file extension

Device Driver

System Files

DTD file extension

Document Type Definition File

Developer Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

EXE file extension

Windows Executable File

Executable Files

FLA file extension

Adobe Flash Animation

Developer Files

ICNS file extension

Mac OS X Icon Resource File

System Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

NES file extension

Nintendo (NES) ROM File

Game Files

PY file extension

Python Script

Developer Files

ROM file extension

N64 Game ROM File

Game Files

RPM file extension

Red Hat Package Manager File

Compressed Files

TTF file extension

TrueType Font

Font Files

XCODEPROJ file extension

Xcode Project

Developer Files