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

APK file extension

Android Package File

Executable Files

ASPX file extension

Active Server Page Extended File

Web Files

C file extension

C/C++ Source Code File

Developer Files

DTD file extension

Document Type Definition File

Developer Files

DXF file extension

Drawing Exchange Format File

CAD Files

GED file extension

GEDCOM Genealogy Data File

Data Files

ICNS file extension

Mac OS X Icon Resource File

System Files

JAR file extension

Java Archive File

Executable Files

KEYCHAIN file extension

Mac OS X Keychain File

Data Files

MAX file extension

3ds Max Scene File

3D Image Files

MPG file extension

MPEG Video File

Video Files

PRF file extension

Outlook Profile File

Settings Files

ROM file extension

N64 Game ROM File

Game Files

RPM file extension

Red Hat Package Manager File

Compressed Files

ZIP file extension

Zipped File

Compressed Files