Non-living things are not composed of cells, as cells are the smallest unit of life. Small organisms such as bacteria and protists are only composed of a single cell, but are alive.
Living things are composed of the same chemical elements as non-living things, but all living organisms have cells in common. When a living thing is composed of more than one cell, it is referred to as multicellular. Cells arranged together in a certain way form tissue. Tissues then form organs, which form organ systems. Organ systems form an individual organism, such as a human being or an animal.