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

ASP file extension

Active Server Page

Web Files

ASPX file extension

Active Server Page Extended File

Web Files

BAK file extension

Backup File

Backup Files

BAT file extension

DOS Batch File

Executable Files

CBR file extension

Comic Book RAR Archive

Compressed Files

CRX file extension

Chrome Extension

Plugin Files

CSR file extension

Certificate Signing Request File

Web Files

DEB file extension

Debian Software Package

Compressed Files

INI file extension

Windows Initialization File

Settings Files

MSI file extension

Windows Installer Package

Misc Files

PPT file extension

PowerPoint Presentation

Data Files

RA file extension

Real Audio File

Audio Files

WAV file extension

WAVE Audio File

Audio Files

XHTML file extension

Extensible Hypertext Markup Language File

Web Files

XLR file extension

Works Spreadsheet

Spreadsheet Files