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

OBJ file extension

Wavefront 3D Object File

3D Image Files

DDS file extension

DirectDraw Surface

Raster Image Files

MOBI file extension

Mobipocket eBook

eBook Files

DOC file extension

Microsoft Word Document

Text Files

WSF file extension

Windows Script File

Executable Files

AIF file extension

Audio Interchange File Format

Audio Files

7Z file extension

7-Zip Compressed File

Compressed Files

BIN file extension

Binary Disc Image

Disk Image Files

MAX file extension

3ds Max Scene File

3D Image Files

JSP file extension

Java Server Page

Web Files

ASX file extension

Microsoft ASF Redirector File

Video Files

EPUB file extension

Open eBook File

eBook Files

YUV file extension

YUV Encoded Image File

Raster Image Files

TIFF file extension

Tagged Image File Format

Raster Image Files

THM file extension

Thumbnail Image File

Raster Image Files