So you're interested in growth hacking. Maybe you know a little about it, maybe you've never heard about it, maybe you're the inventor of the term and you're scoping out the competition (hi, Sean!). No matter who you are, you're not looking to make a business grow - your looking to make a business erupt like Vesuvius. You're looking to spread like blue jeans and the Beatles - to become an uninterrupted facet of modern life, like automobiles, cable television, and Facebook.

In the digital age, there is such a proliferation of choice and competition that it is no longer enough for a business to "get people in the door". A consumer can easily try a product, make a snap decision on its relative value, and leave with no more effort than clicking "unsubscribe" to the first auto-drip email that arrives in their inbox. Recent societal and technological developments have introduced an urgent need for online businesses to focus on retention and engagement. The more engaged users are, the more likely they are to refer friends, family, professional contacts and like-minded people to their particular community, which in itself organically drives acquisition. This results in a larger user base, which increases engagement and thus retention and referral.

This is a concept known as virality, which is the evolution of the concept of "word-of-mouth marketing". Virality is the way that you accomplish that benevolent positive feedback loop. As a growth hacker, virality is what you are about, because you are responsible for driving explosive, exponential growth for a company, a la Twitter, YouTube, and Pinterest. Your job is to do the years of work that make something an overnight success. After the roar of the crowd has subsided and their fickle attention spans start to scan the horizon for the next big thing, it's your job to shake it all up, reengage them, and turn your huge growth gains into a long-term investment.