It was December, 2013 when this web-page was published and scared many! Lot of people thought it to be fake because they didn't understand it completely.
It's quite old but I decided to share it anyway because it provides greater insight about the security of bitcoin and other similar alt-coins.
For those of you who don't fully understand/missed this, here's what's actually happening:
Private keys are basically numbers from 1 to 1.15792E77.(slightly less than that) Every page lists 128 private keys starting from 1.
Each time a specific page is requested, 128 keys belonging to that page and their corresponding addresses are calculated and displayed.
In page 2 for example private keys range from 129 till 256 and so on..
He was right in saying that it has all addresses but he lied by saying that it's a database. Obviously he was joking but it showed how strong the security of math behind Bitcoin is.
So it isn't a database. And such a database cannot be made because read this article here. [reddit article]
If you have questions, read the reddit article above. If you still don't understand ask me in comments below.