Getting Things Done (GTD) is a personal productivity methodology developed by David Allen in 2001, designed to help individuals achieve stress-free productivity by capturing all commitments, clarifying actionable steps, organizing systematically, reviewing regularly, and engaging with work appropriately. The core principle is that your mind is for having ideas, not holding them—by externalizing all open loops into a trusted system, you free mental bandwidth for creative thinking and appropriate engagement. GTD achieves what Allen calls a "mind like water" state: responding appropriately to whatever appears without overreaction or underreaction, enabling peak performance through complete clarity on all commitments.