To understand that, you'd need to know just how bad search was before Google. Search wasn't even a "thing" on its own, it was usually merely a feature of large portals (AltaVista, AOL) which were large, slow, cumbersome and gave pretty irrelevant search results. At that time, search relied mostly on the meta tags of the pages themselves - which was easy to game and lead to a lot of spam in the search results back then already.

Google's clean interface (basically just a search box) was so revolutionary that it's hard to comprehend today - I still remember it took me a few days to even take it serious, it was so thin and lightweight. PageRank was a gigantic step forward in SERP relevancy and even though it was gamed eventually by link farms and paid backlinks, it took a lot of time and effort and the first few years saw few spammers.

> Was it just the technological advance of Google-Matrix (Page Rank) and Map-Reduce?

Well, yes, it was simply that. It was the difference between a search engine that works and one that doesn't. For example, most sites back then had tons of text with the same color of the background, with words that would get you an higher rank on the previous generation of search engines. Also, the search engines had very heavy pages, mostly with news, and they were known as "portals". Google was a blast in comparison.

The dirt-simple UI and fast loading times helped.

Before Google, the dominant search engine was AltaVista, which was awful. The UI was so crowded that you had to search for the search bar, and it was so full of graphics that if you were on dialup, loading took forever unless you turned images off.

And, yeah, PageRank helped. It wasn't uncommon for you to find what you were looking for on page 3 or 4. Google had what you were looking for on page 1, always. In fact, pre-Google search was so bad that if you were looking for anything obscure, you had to use multiple search engines. When I'd get serious about finding something, I'd fire up AltaVista, Infoseek (Disney/ABC/Go.com), Hotbot, WebCrawler (AOL), etc. in separate browser windows and search on all of them. And for the lazy, there was MetaCrawler, which automated this; I didn't use it often, mostly because I kept forgetting about it, but when I remembered to use it, it was a godsend.

My mother introduced me to Google back in the day. She and several of her friends agreed that it was amazing because it was fast, simple, and got out of your way. And back then, that's exactly what it was:

http://royal.pingdom.com/2008/09/05/googles-first-website-fr...

At the time, their main competitors were already expanding into other markets, and Google was refreshing for doing one thing and doing it well, compared to its competition. It didn't clutter, it didn't try to distract with other services that they offered. It simply gave you the results you queried as a plain list of links, and got out of your way so you could browse those links at your leisure.

The day that I abandoned Altavista for Google was the day that several technical queries brought up porn -- AltaVista had been pwned by porn-pushing keyword stuffers.

At that point Google had a smaller index, which hurt their results, but I thought that was better than getting porn results while at work.