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

BIN file extension

Binary Disc Image

Disk Image Files

CLASS file extension

Java Class File

Developer Files

CSR file extension

Certificate Signing Request File

Web Files

ISO file extension

Disc Image File

Disk Image Files

JAVA file extension

Java Source Code File

Developer Files

JS file extension

JavaScript File

Web Files

LUA file extension

Lua Source File

Developer Files

MAX file extension

3ds Max Scene File

3D Image Files

MDB file extension

Microsoft Access Database

Database Files

MOV file extension

Apple QuickTime Movie

Video Files

PAGES file extension

Pages Document

Text Files

RPM file extension

Red Hat Package Manager File

Compressed Files

RTF file extension

Rich Text Format File

Text Files

WAV file extension

WAVE Audio File

Audio Files

WMV file extension

Windows Media Video File

Video Files