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

ASX file extension

Microsoft ASF Redirector File

Video Files

CUR file extension

Windows Cursor

System Files

DTD file extension

Document Type Definition File

Developer Files

DXF file extension

Drawing Exchange Format File

CAD Files

EPUB file extension

Open eBook File

eBook Files

FLA file extension

Adobe Flash Animation

Developer Files

GZ file extension

Gnu Zipped Archive

Compressed Files

JAR file extension

Java Archive File

Executable Files

M4A file extension

MPEG-4 Audio File

Audio Files

MOBI file extension

Mobipocket eBook

eBook Files

MOV file extension

Apple QuickTime Movie

Video Files

MSG file extension

Outlook Mail Message

Text Files

PL file extension

Perl Script

Developer Files

VCD file extension

Virtual CD

Disk Image Files

3DS file extension

3D Studio Scene

3D Image Files