Cells

A cell is a categorical level of organization on the microscopic level within biological organisms. One cell is defined as an accumulation of molecules which forms a single functioning, living concept. A cell is often microscopic, and it is the smallest, most basic form of life, both according to the structural levels of life and according to physical size. It may have organelles, which are components and structures found on a cellular level like their greater counterparts, organs.

A grouping of cells, especially those which possess similar embryonic origins and similar functions at maturity, is known as a tissue.