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

CRX file extension

Chrome Extension

Plugin Files

DAT file extension

Data File

Data Files

DB file extension

Database File

Database Files

DBF file extension

Database File

Database Files

HTML file extension

Hypertext Markup Language File

Web Files

MSI file extension

Windows Installer Package

Misc Files

NES file extension

Nintendo (NES) ROM File

Game Files

PDF file extension

Portable Document Format File

Layout Files

PSD file extension

Adobe Photoshop Document

Raster Image Files

PY file extension

Python Script

Developer Files

RSS file extension

Rich Site Summary

Web Files

RTF file extension

Rich Text Format File

Text Files

XLR file extension

Works Spreadsheet

Spreadsheet Files