Getting a previously existing version of a website

No man ever steps in the same river twice,
for it’s not the same river and he’s not the same man.
Heraclitus, in Diogenes Laertius, Lives

The information on the net changes quickly — which becomes a problem if you find a reference to a website that doesn’t exist anymore or has changed in the meantime. However, there is a website that can help (hopefully this website never changes ;-)): The Internet Archive. They do occasional snapshots of websites and store them for access. So, if something on the Internet changes they might have the previous version:

Internet Archive:

Wayback Machine (specialized on web pages):

Very, very convenient.