You Could Have Invented PageRank
In 1996, search engines like AltaVista matched keywords, frustrating users. Sergey Brin and Larry Page solved this with PageRank, an algorithm that ranks pages by reputation and links. This post breaks down PageRank's core idea—pages share rank via links—into a simple, readable Python program. It argues that with the right perspective, anyone could have stumbled upon this billion-dollar algorithm.
If you run these updates a bunch of times, you eventually end up with a rank for each of the pages that basically tells you how important they are.
- inigyou
Importantly, PageRank doesn't work today - you need something else. It was one of many possible ranking hacks, and one that worked at the particular time in that particular state of the web where nobody was gaming links because PageRank didn't exist yet. Maybe you could invent a good ranking algorithm for the modern internet, perhaps just the reciprocal of the number of ads on the page, minus its AI detector score, but probably not that.
Unimportantly, it's named after Larry Page, not after the fact that it ranks pages.
- jefflinwood
I actually built this, and shipped it, in 1996, with no knowledge of page rank, citation analysis, or bibliometrics, for an internal/external search engine for the Envirolink web site. Envirolink was a directory of environmental web sites, so they already had a list of URLs to crawl. The reason it was feasible to build was that it was a fairly constrained list of URLs, it wasn't the entire web.
I didn't really know what I was doing (I was 17), but it was an awesome unpaid summer internship. There were two parts of the search engine - a crawler and the search engine. Both were written in Perl.
- ianbooker
PageRank is fascinating, since it is so easy to explain.
Yet, this is not even half the work. It like a third of the way.
Before you could have invented PageRank, you must think in graphs. That is possible in 1996, but not as widespread as today.
After you invented PageRank, you still need to deploy it. Again, possible but challenging as well. Is Python performant enough in 96? Can you afford more than 4MB RAM?
At least Lego will not sue you for using their bricks to build a server rack in 1996.
- nayuki
Here are two excellent videos that explain and visualize the PageRank algorithm:
* [2020-06-17] Spanning Tree - "How Google's PageRank Algorithm Works" (5m16s): https://www.youtube.com/watch?v=meonLcN7LD4
* [2022-05-23] Reducible - "PageRank: A Trillion Dollar Algorithm" (25m25s): https://www.youtube.com/watch?v=JGQe4kiPnrU
- smcg
Well, I was a child in 1996, so probably not.
Tying relevancy to link frequency was definitely a novel idea at the time, even if it seems "obvious" or simple in retrospect.