This document provides an overview of the Lean Startup methodology developed by Eric Ries. It discusses that a startup is an organization designed to create a new product or service under conditions of uncertainty. The Lean Startup methodology advocates for the build-measure-learn feedback loop to test hypotheses, build minimum viable products, measure customer feedback, and iterate based on validated learning. It provides examples of how companies like Airbnb have used this process and discusses when to pivot or persevere based on measured metrics.