The basic (elementary) unit of the biological systematics of organisms.

The cell is considered the smallest structural component of any living organism with the exception of viruses. Viruses are made up of genetic information and a protein coat. Cellular organisms can be made up of one or many cells. In unicellular organisms, all processes take place in one cell. Cells can connect to form tissues and organs. Then some cells become dependent on others, since different processes take place in different cells. But in most multicellular organisms, damage to some cells does not cause the death of the entire organism.