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

ZIP file extension

Zipped File

Compressed Files

SYS file extension

Windows System File

System Files

EPUB file extension

Open eBook File

eBook Files

H file extension

C/C++/Objective-C Header File

Developer Files

MID file extension

MIDI File

Audio Files

JAR file extension

Java Archive File

Executable Files

DOC# file extension

Microsoft Word Document

Text Files

DBF file extension

Database File

Database Files

TOAST file extension

Toast Disc Image

Disk Image Files

UUE file extension

Uuencoded File

Encoded Files

SWF file extension

Shockwave Flash Movie

Video Files

DMP file extension

Windows Memory Dump

System Files

CSS file extension

Cascading Style Sheet

Web Files

C file extension

C/C++ Source Code File

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files