"If you're building a technology platform, making it "social" really means figuring out what the nodes, edges, and jumping functions should be. One way to do this is to work backwards. What should the experience feel like at scale? Do users care about what other people are doing on the network, or do they really care about other types of objects, like tags and categories? On Meetup, the most popular tags are in effect functions of choices people make, which might inform future suggestions, so they're almost a layer on top of the users themselves."