Extreme Programming (XP) is an agile software development methodology that focuses on customer satisfaction and rapid feedback. It utilizes practices like pair programming, simple design, small releases, and testing. Scrum is another agile methodology using a product backlog, sprints, and daily stand-ups. Development teams are self-organizing and work in sprints to deliver working software. Other methodologies discussed include Dynamic Systems Development Method (DSDM), Feature-Driven Development (FDD), Crystal, and Lean Software Development (LSD).