Picture this, the year is 1996. You find yourself frustrated with the incumbent search engines like Alta Vista, which primarily does a content-based search (it’ll give you an article on “Hotels for Chickens” if you search “Hotels” because the word matches). There’s gotta be a better way, right? Well, in hindsight, of course. Sergey Brin and Larry Page came up with this precise algorithm, i.e., Page Rank, which was one of the key algorithms that helped catapult Google into a household name and made them tons of money. Both Sergey and Larry were grad students at Stanford, so their coming up with such an amazing algorithm doesn’t seem surprising. However, the question is, could you have stumbled upon the same? I think yes.

Page Rank, at its core, symbolizes these basic properties. Every page has a “rank” or reputation. A page shares its “rank” with another page by linking to it, sort of giving it a mark of approval. A page’s total rank/reputation is some minimum summed with all the reputation it gets from its neighbors (whoever links it).

To solidify this with a concrete example. Imagine a page (say BBC News) has a reputation of 50 and it links to 5 different pages. Assume that it distributes 80% (40) of its reputation to its linkees (the remaining being distributed uniformly to all pages). Then each of its linkees gets, from BBC, a total of 40/5 = 8 points.

And that’s about it. 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. Congratulations, if you ever find yourself in 1996, you know what to do to become a billionaire!