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

COM file extension

DOS Command File

Executable Files

MSI file extension

Windows Installer Package

Misc Files

VCXPROJ file extension

Visual C++ Project

Developer Files

7Z file extension

7-Zip Compressed File

Compressed Files

CBR file extension

Comic Book RAR Archive

Compressed Files

UUE file extension

Uuencoded File

Encoded Files

BIN file extension

Binary Disc Image

Disk Image Files

CSS file extension

Cascading Style Sheet

Web Files

MID file extension

MIDI File

Audio Files

JAR file extension

Java Archive File

Executable Files

SLN file extension

Visual Studio Solution File

Developer Files

CLASS file extension

Java Class File

Developer Files

M4A file extension

MPEG-4 Audio File

Audio Files

BMP file extension

Bitmap Image File

Raster Image Files

RA file extension

Real Audio File

Audio Files