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

CRX file extension

Chrome Extension

Plugin Files

DAT file extension

Data File

Data Files

JS file extension

JavaScript File

Web Files

PIF file extension

Program Information File

Executable Files

PPTX file extension

PowerPoint Open XML Presentation

Data Files

SQL file extension

Structured Query Language Data File

Database Files

TEX file extension

LaTeX Source Document

Text Files

TTF file extension

TrueType Font

Font Files

WPD file extension

WordPerfect Document

Text Files

XCODEPROJ file extension

Xcode Project

Developer Files

XLR file extension

Works Spreadsheet

Spreadsheet Files

3GP file extension

3GPP Multimedia File

Video Files