Swallowing is the perception of taste, consistency, and size of the food taken into the mouth, chewing and creating a bolus, and the safe, effective, and timely delivery of this bolus from the oral cavity to the stomach through the pharynx and esophagus. Swallowing has two critical biological properties. The first is nutrition, and the second is airway protection. In swallowing disorder, life-threatening respiratory conditions such as aspiration can occur at any time, so it is essential to understand and maintain awareness of dysphagia. Physiologically, it consists of three phases: oral, pharyngeal, and esophageal phases. In the oral phase, taking the food into the mouth, closing the lips, positioning the food in the mouth by tongue and jaw movements and contraction of the cheek muscles, chewing, preventing escape from the mouth to the pharynx by the downward movement of the soft palate, then directing the food to the root of the tongue by elevating the tongue, and the swallowing reflex by contacting the bolus with the tonsillar plicas includes the period until triggering. It is controlled voluntarily. In order to form the bolus in this phase, adequate salivation, oral taste, temperature proprioception senses, and muscle strength are required. The oral phase duration varies depending on the type and volume of the food.