This document discusses growth hacking strategies used by early internet companies like Hotmail to achieve rapid growth. It defines growth hacking as a set of tactics and best practices for acquiring, activating, and retaining users. Some key tactics discussed include viral growth, A/B testing landing pages, optimizing the user lifecycle funnel, and identifying bottlenecks. The document provides examples of notable growth hacks from companies like Dropbox, Path, and Eventbrite.