This document provides an introduction to the concept of growth hacking. It discusses growth hacking as a data-driven approach to growing a user base through rapid experimentation and optimization of digital touchpoints. The document outlines the lean marketing funnel framework and various growth hacking tactics, including setting up analytics, A/B testing, creating landing pages, inbound marketing, email marketing, paid channels/remarketing, public relations, and building viral mechanisms. It emphasizes the importance of testing, measuring, learning, and refining to find effective growth strategies in a rapidly changing market.