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

7Z file extension

7-Zip Compressed File

Compressed Files

CSR file extension

Certificate Signing Request File

Web Files

CFM file extension

ColdFusion Markup File

Web Files

LUA file extension

Lua Source File

Developer Files

BAK file extension

Backup File

Backup Files

SRT file extension

SubRip Subtitle File

Video Files

PART file extension

Partially Downloaded File

Misc Files

CLASS file extension

Java Class File

Developer Files

TARGZ file extension

Compressed Tarball File

Compressed Files

H file extension

C/C++/Objective-C Header File

Developer Files

PS file extension

PostScript File

Vector Image Files

FLV file extension

Flash Video File

Video Files

WAV file extension

WAVE Audio File

Audio Files

XCODEPROJ file extension

Xcode Project

Developer Files

ROM file extension

N64 Game ROM File

Game Files