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

C file extension

C/C++ Source Code File

Developer Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

AZW file extension

Amazon Kindle eBook File

eBook Files

CSR file extension

Certificate Signing Request File

Web Files

M4A file extension

MPEG-4 Audio File

Audio Files

TORRENT file extension

BitTorrent File

Misc Files

HTML file extension

Hypertext Markup Language File

Web Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

7Z file extension

7-Zip Compressed File

Compressed Files

PIF file extension

Program Information File

Executable Files

TARGZ file extension

Compressed Tarball File

Compressed Files

PDF file extension

Portable Document Format File

Layout Files

DNG file extension

Digital Negative Image File

Camera Raw Files

IBOOKS file extension

Multi-Touch iBook

Data Files