What is the difference between “image/png” and “image/x-png”?

Question

What is the difference between \"image/png\" and \"image/x-png\"?

Answer 1

image/x-png was the type before PNG was accepted by the IANA as an official mime type.

http://www.iana.org/assignments/media-types/image/

The official image/png MIME type for PNG, approved on 14 October 1996

http://www.w3.org/Graphics/PNG/