PHP - Opening/Reading files?

I found a site where, when you upload a file, it opens it and extracts an image and a description from it. How is that possible?

 

Anymore details? What is the format of the file? (extension, type)
Could you also provide the URL of the site?

 

Extensions are .mpq

Site is http://www.epicwar.com

 

MPQ is a game-file. Details can be viewed at a number of sites, including http://en.wikipedia.org/wiki/MPQ

Because the image(s) and description(s) are already in the file, it's easy enough to extract. It is same, albeit more complex, as opening a text file and "extracting" the text.
For any given file type, if you know the file format details, you can write (or find) a program that will extract the data in the desired format.

I'm not sure I answered your question, because as some StarTrek dude said, "It is difficult to answer, when one does not understand the question."