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

PSD file extension

Adobe Photoshop Document

Raster Image Files

RM file extension

Real Media File

Video Files

MPG file extension

MPEG Video File

Video Files

CRX file extension

Chrome Extension

Plugin Files

TEX file extension

LaTeX Source Document

Text Files

SDF file extension

Standard Data File

Data Files

C file extension

C/C++ Source Code File

Developer Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

CUE file extension

Cue Sheet File

Disk Image Files

MP3 file extension

MP3 Audio File

Audio Files

7Z file extension

7-Zip Compressed File

Compressed Files

PSPIMAGE file extension

PaintShop Pro Image

Raster Image Files

HTM file extension

Hypertext Markup Language File

Web Files

IFF file extension

Interchange File Format

Audio Files

HQX file extension

BinHex 4.0 Encoded File

Encoded Files