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

ACCDB file extension

Access 2007 Database File

Database Files

BAK file extension

Backup File

Backup Files

CS file extension

Visual C# Source Code File

Developer Files

CSS file extension

Cascading Style Sheet

Web Files

CSV file extension

Comma Separated Values File

Data Files

DEB file extension

Debian Software Package

Compressed Files

EXE file extension

Windows Executable File

Executable Files

FLV file extension

Flash Video File

Video Files

JAR file extension

Java Archive File

Executable Files

JAVA file extension

Java Source Code File

Developer Files

M file extension

Objective-C Implementation File

Developer Files

MSI file extension

Windows Installer Package

Misc Files

ODT file extension

OpenDocument Text Document

Text Files

PNG file extension

Portable Network Graphic

Raster Image Files

SRT file extension

SubRip Subtitle File

Video Files