This document provides an introduction to Lean, Agile, Scrum, and XP. It defines Lean as focusing on identifying value and optimizing processes. Agile emphasizes responding quickly to change through principles like valuing individuals, working software, and customer collaboration. Scrum is a framework that uses short cycles, daily stand-ups, and product backlogs to organize complex work. XP includes practices like pair programming, test-driven development, and collective code ownership.