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

RTF file extension

Rich Text Format File

Text Files

3DS file extension

3D Studio Scene

3D Image Files

EPUB file extension

Open eBook File

eBook Files

CPP file extension

C++ Source Code File

Developer Files

PAGES file extension

Pages Document

Text Files

CRDOWNLOAD file extension

Chrome Partially Downloaded File

Misc Files

TMP file extension

Temporary File

Backup Files

ASPX file extension

Active Server Page Extended File

Web Files

DDS file extension

DirectDraw Surface

Raster Image Files

GPX file extension

GPS Exchange File

GIS Files

ICNS file extension

Mac OS X Icon Resource File

System Files

CER file extension

Internet Security Certificate

Web Files

7Z file extension

7-Zip Compressed File

Compressed Files

LOG file extension

Log File

Text Files

TIF file extension

Tagged Image File

Raster Image Files