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

RM file extension

Real Media File

Video Files

PCT file extension

Picture File

Layout Files

RSS file extension

Rich Site Summary

Web Files

H file extension

C/C++/Objective-C Header File

Developer Files

CUR file extension

Windows Cursor

System Files

JAR file extension

Java Archive File

Executable Files

DB file extension

Database File

Database Files

JAVA file extension

Java Source Code File

Developer Files

SWF file extension

Shockwave Flash Movie

Video Files

KEY file extension

Keynote Presentation

Data Files

APK file extension

Android Package File

Executable Files

7Z file extension

7-Zip Compressed File

Compressed Files

C file extension

C/C++ Source Code File

Developer Files

CAB file extension

Windows Cabinet File

System Files

DAT file extension

Data File

Data Files