This document introduces the Lean Startup methodology for launching companies. It discusses replacing traditional business plans and linear execution with customer development, hypothesis testing, and iterative product development and validation. The Lean Startup process involves creating a business model canvas, conducting customer interviews to test assumptions, designing experiments to validate hypotheses, and using the results to pivot, iterate, or persevere. Examples are provided of how companies have leveraged these Lean principles to develop products through rapid experimentation and learning.