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

ACCDB file extension

Access 2007 Database File

Database Files

ASP file extension

Active Server Page

Web Files

CPL file extension

Windows Control Panel Item

System Files

CRX file extension

Chrome Extension

Plugin Files

GZ file extension

Gnu Zipped Archive

Compressed Files

INI file extension

Windows Initialization File

Settings Files

MP3 file extension

MP3 Audio File

Audio Files

OBJ file extension

Wavefront 3D Object File

3D Image Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

RSS file extension

Rich Site Summary

Web Files

RTF file extension

Rich Text Format File

Text Files

SQL file extension

Structured Query Language Data File

Database Files

VB file extension

VBScript File

Executable Files

XLSX file extension

Microsoft Excel Open XML Spreadsheet

Spreadsheet Files

ZIPX file extension

Extended Zip File

Compressed Files