Deglutition is the physical act of swallowing — the coordinated muscular sequence that moves food or liquid from the mouth to the stomach. It runs in three phases: the voluntary oral phase, where the tongue shapes the chewed mass into a bolus and pushes it back; the pharyngeal phase, an involuntary reflex that seals the airway with the epiglottis while muscles squeeze the bolus down the throat; and the oesophageal phase, where waves of peristalsis carry it to the stomach. The whole sequence takes seconds and involves dozens of muscles and cranial nerves working in precise order. Food scientists meet deglutition in dysphagia — swallowing disorders common in stroke and old age — where texture-modified diets of soft, moist, cohesive foods are engineered to be swallowed safely without aspiration into the lungs.