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

ASP file extension

Active Server Page

Web Files

BMP file extension

Bitmap Image File

Raster Image Files

DNG file extension

Digital Negative Image File

Camera Raw Files

ICNS file extension

Mac OS X Icon Resource File

System Files

JAVA file extension

Java Source Code File

Developer Files

LOG file extension

Log File

Text Files

LUA file extension

Lua Source File

Developer Files

MPG file extension

MPEG Video File

Video Files

PCT file extension

Picture File

Layout Files

PRF file extension

Outlook Profile File

Settings Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

SH file extension

Bash Shell Script

Developer Files

UUE file extension

Uuencoded File

Encoded Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files