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

ASF file extension

Advanced Systems Format File

Video Files

BMP file extension

Bitmap Image File

Raster Image Files

CUR file extension

Windows Cursor

System Files

DBF file extension

Database File

Database Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

HTM file extension

Hypertext Markup Language File

Web Files

HTML file extension

Hypertext Markup Language File

Web Files

JAVA file extension

Java Source Code File

Developer Files

LNK file extension

Windows File Shortcut

System Files

MDF file extension

Media Disc Image File

Disk Image Files

ODT file extension

OpenDocument Text Document

Text Files

PART file extension

Partially Downloaded File

Misc Files

PCT file extension

Picture File

Layout Files

PPS file extension

PowerPoint Slide Show

Data Files

WMA file extension

Windows Media Audio File

Audio Files