Growth hacking is a marketing technique used by startups that focuses on low-cost and innovative alternatives to traditional marketing. It involves using creativity, analytics, and social metrics to sell products and gain exposure through techniques like SEO, website analytics, content marketing, and A/B testing. Growth hackers prioritize growth over budgets by analyzing the customer acquisition funnel to identify opportunities to improve conversion rates at each stage - acquisition, activation, retention, revenue, and referrals. The goal is to brainstorm experiments, prioritize ideas, develop hypotheses, test changes, and systematize optimized processes into a repeatable "growth machine" approach focused on continuous improvement.