[unconed]

The thing that made Google unique is that they ranked pages according to the links between them (i.e. PageRank), as opposed to more traditional document ranking methods that are keyword based.

As a result, Google found showed you content that people liked (and linked to). From the end-user's perspective, Google search was noticeably better and more relevant.

As far as I know, it was the first massive application of data mining graphs, which now drives social networking, content recommendations and more.