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

CLASS file extension

Java Class File

Developer Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

CSV file extension

Comma Separated Values File

Data Files

DESKTHEMEPACK file extension

Windows 8 Desktop Theme Pack File

System Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

DWG file extension

AutoCAD Drawing Database File

CAD Files

EPUB file extension

Open eBook File

eBook Files

GIF file extension

Graphical Interchange Format File

Raster Image Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

PRF file extension

Outlook Profile File

Settings Files

ROM file extension

N64 Game ROM File

Game Files

TGA file extension

Targa Graphic

Raster Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

UUE file extension

Uuencoded File

Encoded Files

3G2 file extension

3GPP2 Multimedia File

Video Files