Build-Measure-Learn is a feedback loop that allows startups to continue the experimentation and innovation that made them successful in the first place without stalling production and or losing revenue. The first step is to build an MVP. The second is to measure the viability through customer feedback and quantitative data. The third step, before building again, is to learn from analyzing the feedback and data and make the appropriate adjustments to features and services. This cycle is repeatable throughout the lifespan of the product, and Ries recommends cycling through these steps as quickly as possible in the early stages.

The engine of growth comprises new products, new features, new marketing programs, and new business strategies that increase the production and revenue of the company. There are three engines of growth: sticky, viral, and paid. Sticky growth refers to customer retention while viral growth spreads through word of mouth. Paid growth is any form of paid advertising that leads to new customers. Ries recommends that new startups focus on one engine of growth at first and use validated learning to assess the method’s efficacy before expanding to other growth engines.