The ingestion of food is the process of intake of food by an organism and human beings ingest food through their mouth. The ingested food is processed by breaking the food into small pieces by the teeth which is then lubricated by the saliva so that it can be swallowed with the help of the tongue.

The process of breakdown of complex food particles into simpler absorbable substances is known as digestion. The different steps in the digestion process are ingestion, propulsion, mechanical digestion, chemical digestion, absorption, and defecation.

Absorption is the process of passing of digested food into the bloodstream and lymph vessels by the digestive system. In human beings, this process mainly takes place in the small intestine which contains the finger-like projections known as villi.

Assimilation is the process of movement of digested food molecules in their simpler forms into the cells of the body, where they undergo the process of cellular respiration to provide us energy.

The process of removal of undigested solid waste materials from our body is known as egestion. The waste materials are removed in the form of faeces through the anus. It is a voluntary process, carried out by mass peristaltic movement.