The Fourth Phase refers to a state of water that exists between liquid and solid forms, often called "exclusion zone" water. This phase is characterized by a structured arrangement of water molecules, which can occur near hydrophilic surfaces. It plays a crucial role in biological processes and is essential for cellular function. Research on the Fourth Phase has been popularized by Dr. Gerald Pollack, who suggests that this structured water can store energy and influence biological systems. Understanding this phase may lead to new insights in fields like biochemistry and medicine, potentially impacting hydration and cellular health.