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

CBR file extension

Comic Book RAR Archive

Compressed Files

CPP file extension

C++ Source Code File

Developer Files

CSV file extension

Comma Separated Values File

Data Files

DOCX file extension

Microsoft Word Open XML Document

Text 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

M4A file extension

MPEG-4 Audio File

Audio Files

PKG file extension

Mac OS X Installer Package

Compressed Files

RA file extension

Real Audio File

Audio Files

SDF file extension

Standard Data File

Data Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

VOB file extension

DVD Video Object File

Video Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

3G2 file extension

3GPP2 Multimedia File

Video Files