Google and cached info

I was reading the news and saw this article. Could someone explain to me how this actually works. I was thinking about it but it's not making a whole lot of sense to me. How is google able to find cached info on photocopies.Is this similar to the credit card hack with google. This is purely for my own educational knowledge not anything malicious if this question falls in that category. You don't have to tell the actual search terms just the logic on how this works. Thanks

http://www.ebcvg.com/news.php?id=3828

Google just download the page locallly (Without image and stuff, only the html) and keep it on in server.