File extension guide is a helpfull information site that is dedicated to describing computer file formats and how they relate to file extensions mainly on Microsoft Windows platform and other operating systems like Apple Mac OS X or Linux/Unix.

What is file extension?

A computer filename extension is usually a three or more letters combination added to the end of file name and separated by a dot character. File extension indicates the encoding convention (file format, file type) of its contents. Operating system like Microsoft Windows registers and associates file extension to a program(s). You can then by using some file manager (Windows Explorer, Total Commander, Apple Finder etc.) operate with file simple double-clicking at the file and you can view, open and edit, play, convert or extract desired file type specified by its file extension. The operating system does default action based on registered file extensions, installed applications or custom user settings - by default, it runs default application. For example: by clicking on music file (usually mp3 file extension) it opens default player and play the music file.

You can simply start to search file extension information by clicking at first letter link and browse for file types with extension by the letter it starts with.

This database was put together as an answer to overwhelming demand from millions of users who are confused about what application best to use to open each file. Now that files are exchanged over the internet on a regular basis this problem has become even more severe.

Display file extensions at your Windows operating system

By default, Windows is configured to hide filename extensions, the (usually three-leter) portion of the filename following the period. Aside from creating a knowledge gap between experienced and inexperienced users, this "feature" also can make it difficult to differentiate files with the same filename prefix. Overall, hiding filename extensions makes Windows more difficult to use.

To display file extensions at your Windows follow these steps:
- Open My Computer, and select Folder Options from the Tools menu (or choose Options from the View menu in Windows 95). If you don't see horizontal top menu, pressing Alt key may help to show it.
- Click on the View tab and turn off Hide file extensions for known file types, and press OK.


Unlike other similar websites that can be found on the Internet that are filled with huge and unuseful generated content hard to interpret, content of this file extension guide website is written by a team of human technicaly skilled writers.

Every article provides simple information on how to open various file type and typical programs that you can use for it.

Filling this website with information and maintaining its content is hard and continuous work. We always welcome feedback and suggestions that can be submitted by visiting About page. However since there are many users visiting this website and because our team is quite small we may not be able to follow up personally on every support request. Thank you for your understanding.