Filename Extensions
If you are seeking information about file extensions, then you are in the right place at right time.

Frequently Asked Questions

Basic questions about file extensions are answered on this page. If you have any questions that were not answered on this page, please contact us.

What is a file extension?
A filename extension is an extra set of (usually) alphanumeric characters that is appended to the end of a filename to allow computer users (as well as various pieces of software on the computer system) to quickly determine the type of data stored in the file. It is one of several popular methods for distinguishing between file formats. For more information about the file extension, see the Wikipedia article.
Can I change the extension of files?
Changing the filename extension of a file is not a good idea. When you change a file's extension, you change the way programs on your computer read the file. The problem is, changing the file extension does not change the file format.
How can I change file associations in Windows?
To change file associations:
  • Right-click a file with the extension whose association you want to change, and then click Open With.
  • In the Open With dialog box, click the program whith which you want the file to open, or click Browse to locate the program that you want.
  • Select the Always use the selected program to open this kind of file check box.
What is MIME type?
The MIME type (Multipurpose Internet Message Extension) is an unique identifier string for data format. The browser (like Internet Explorer) uses the MIME type to determine how the data it receives is to be processed, displayed in the browser window, saved to a file or sent to a helper application. Click here for more information.
What is Magic bytes and Magic string?
A magic number is a number embedded at or near the beginning of a file that indicates its file format (i.e., the type of file it is). It is also sometimes referred to as a file signature. Magic numbers are generally not visible to users. However, they can easily be seen with the use of a hex editor, which is a specialized program that shows and allows modification of every byte in a file.
Can I get personal support from
Sorry, cannot provide personal support.
Can I help
Yes. If you find a new extension, a related link or useful information about extensions, then please click on the "Submit New" button at the top of page and contact us.