Recently, I’ve been studying the The Lean Startup by Eric Reis. He talks about various growth engines and I love how it describes viral businesses. So I’m borrowing his concept and adding some thoughts of my own.

For the purposes of this post, I am not discussing creating one viral campaign. I am instead focusing on products or services that are inherently viral themselves. In other words, they don’t use sticky growth (subscriptions) or paid growth (print, TV, radio ads, etc).