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

APP file extension

Mac OS X Application

Executable Files

COM file extension

DOS Command File

Executable Files

JAVA file extension

Java Source Code File

Developer Files

BMP file extension

Bitmap Image File

Raster Image Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

SDF file extension

Standard Data File

Data Files

KMZ file extension

Google Earth Placemark File

GIS Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

7Z file extension

7-Zip Compressed File

Compressed Files

PS file extension

PostScript File

Vector Image Files

TEX file extension

LaTeX Source Document

Text Files

EPUB file extension

Open eBook File

eBook Files

TOAST file extension

Toast Disc Image

Disk Image Files

TXT file extension

Plain Text File

Text Files

AI file extension

Adobe Illustrator File

Vector Image Files