Nutrition is all the activities by which an organism obtains food and utilizes it to carry out life processes (energy production, body repair, growth, and body regulation).

A. Autotrophic nutrition: is a process in which organism synthesize complex organic molecule from simple inorganic molecules to obtain energy. It is the virtue of green plants, algae and some bacteria.

B. Heterotrophic nutrition: is a process in which organism break down complex organic molecule into simple molecule to derive energy. It is the feature of animals, fungi, most protists and bacteria.

It can be categorized into

Parasitic nutrition obtaining nutrients form host organisms.

Saprophytic nutrition refers to external digestion of decaying organic matter, absorbing nutrients through the body wall.

Holozoic nutrition:- Refers to a method of nutrition that is involved in the ingestion and digestion of solid or liquid organic material and the absorption and assimilation of nutrients by the animal body.