How exactly is censored?

I was just browsing through this article, and noticed this quote:

Just to test it, I did a search on the site for democracy.

The top of the list is already suspicious with “”, and then “”. And I could access them with no problems.

So my question is, is supposed to filter these supposed propagandist sites, or is that job taken on by hardware firewalls in China?

Sez Wiki:

However, I searched for 法轮 and got plenty of results, so I don’t know. From what I’ve read Google is self-censoring but I haven’t been able to find any explanation of how it works.

From what I’ve read earlier, though, China has its own firewall and blocking systems in place, and all Google does is skip over results that would be banned in China anyway. So it makes sense that you’d be able to go to from