Engines of Growth

In The Lean Startup, Eric Ries separates growth that compounds from growth that fades. A press mention or a busy launch day brings visitors, but the wave recedes and leaves nothing behind. Sustainable growth means new customers arrive because of something past customers did. They stayed, they told someone, or they paid enough to fund the next ad. That gives three engines. The sticky engine keeps customers. It runs when you win new customers faster than you lose existing ones, so you watch churn against your acquisition rate. The viral engine spreads through use. It runs when each customer brings in more than one new customer on average, which means a viral coefficient above 1. The paid engine buys customers. It runs when a customer's lifetime value exceeds the cost of acquiring them, and the gap pays for the next ad. Each engine demands different experiments and one clear number, so focus on one at a time.