David Allen is a productivity consultant and the author of the book "Getting Things Done: The Art of Stress-Free Productivity." He is widely recognized for his expertise in personal and organizational productivity and has developed the GTD (Getting Things Done) methodology.

In his book, "Getting Things Done," Allen presents a system for managing and organizing tasks and projects to increase productivity and reduce stress. The GTD methodology focuses on capturing all tasks and commitments into an external system, clarifying their meaning and desired outcomes, organizing them effectively, reviewing and updating regularly, and taking appropriate actions. The book has gained significant popularity and has become a widely implemented system for personal and professional productivity.

David Allen has been involved in coaching, training, and consulting with various individuals and organizations, including Fortune 500 companies and government agencies. He continues to speak and conduct workshops on productivity and personal development, sharing his insights and strategies to help individuals and teams enhance their effectiveness and achieve their goals.