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

BAK file extension

Backup File

Backup Files

BAT file extension

DOS Batch File

Executable Files

DOC# file extension

Microsoft Word Document

Text Files

DOCX file extension

Microsoft Word Open XML Document

Text Files

FNT file extension

Windows Font File

Font Files

GBR file extension

Gerber File

Data Files

LNK file extension

Windows File Shortcut

System Files

MP3 file extension

MP3 Audio File

Audio Files

MSG file extension

Outlook Mail Message

Text Files

PDB file extension

Program Database

Database Files

PDF file extension

Portable Document Format File

Layout Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

UUE file extension

Uuencoded File

Encoded Files

YUV file extension

YUV Encoded Image File

Raster Image Files