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

CRX file extension

Chrome Extension

Plugin Files

M4V file extension

iTunes Video File

Video Files

CLASS file extension

Java Class File

Developer Files

UUE file extension

Uuencoded File

Encoded Files

JAR file extension

Java Archive File

Executable Files

LNK file extension

Windows File Shortcut

System Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files

LUA file extension

Lua Source File

Developer Files

AZW file extension

Amazon Kindle eBook File

eBook Files

RPM file extension

Red Hat Package Manager File

Compressed Files

7Z file extension

7-Zip Compressed File

Compressed Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

XCODEPROJ file extension

Xcode Project

Developer Files

THM file extension

Thumbnail Image File

Raster Image Files

ZIP file extension

Zipped File

Compressed Files