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

AVI file extension

Audio Video Interleave File

Video Files

CUR file extension

Windows Cursor

System Files

DXF file extension

Drawing Exchange Format File

CAD Files

GBR file extension

Gerber File

Data Files

GPX file extension

GPS Exchange File

GIS Files

KEY file extension

Keynote Presentation

Data Files

MP3 file extension

MP3 Audio File

Audio Files

PHP file extension

PHP Source Code File

Web Files

RAR file extension

WinRAR Compressed Archive

Compressed Files

SVG file extension

Scalable Vector Graphics File

Vector Image Files

THM file extension

Thumbnail Image File

Raster Image Files

TXT file extension

Plain Text File

Text Files

UUE file extension

Uuencoded File

Encoded Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

ZIPX file extension

Extended Zip File

Compressed Files