What is a social product? This was the question Sandi MacPherson, founder of Quibb posed to me, over lunch earlier this week.

In Startupland, we bandy about terms like social, social media, virality and community when talking about products but it wasn’t until that moment that I stopped to think a bit more about what each word really means. Sandi has thought a lot about these concepts while building Quibb and she has some of the clearest points of view on social products I’ve encountered. These are my notes from that conversation:

Social

Social products have three parts: product (the technology), means of user acquisition/growth (virality) and community (people). The first part, the product, has three features: user profiles, a relationship metaphor (follow/friend) and some kind of data stream/feed for content sharing.

But just building a product with these three features isn’t anywhere close to enough to be successful. Next, the service needs to grow.

Viral

The most natural growth mechanism for social products is through the network itself. This is virality. Viral products use invitation systems to grow quickly. Invitation systems include Facebook Connect, refer-a-friend like Dropbox or team/clan structures like World of Warcraft. Virality is a marketing tactic.

Virality belongs to the same category as SEO, SEM, content marketing, affiliate channels because it’s a customer acquisition vector. Virality differs a bit from these others because successful viral acquisition requires deeper product integration than most advertising. Nevertheless, virality is a marketing tactic, one that is increasingly a science.

Community

But product and viral growth still aren’t enough. The least well understood, documented and discussed but most important element of social products is community. Community is the x-factor.

Communities aren’t products or part of the product. They are amalgamations of people who interact with each other in a certain context and a known set of norms and values. Communities are the lifeblood of social networks. Everything else is just infrastructure - an empty city.

Communities often have very strong culture and values. Reddit encourages a subversive culture. Hacker News champions contentious debate. Tumblr and Instagram fetishize aesthetics. Quibb’s community strives for knowledge.

Fostering communities requires the right chemistry. Mixing the user growth, content moderation, and set of values/norms, to create the substrate for a vibrant city is a constant battle.

Accidental Alchemy

No one I know talks about how to build community. Perhaps that because many of the communities that exist today were created by happy accident. At some point, they just worked and trying to find the root cause of that success is a fool’s errand because the success was the combination of a thousand little things.

Maybe one day we’ll understand better how to consistently grow vibrant communities online. That all begins with first understanding the key parts of a social product.