What is best described as the separation of a material into elements or parts?

The separation of a material into elements or parts is called decomposition. In science, decomposition means breaking a substance or object into simpler components, either through physical processes, chemical reactions, or the activity of living organisms.

In biology, decomposition usually refers to dead plants and animals being broken down by decomposers such as bacteria and fungi. These organisms return nutrients to soil and water, making decomposition a key part of Earth’s nutrient cycles. Organic matter may ultimately become simpler substances such as carbon dioxide, water, mineral salts, and small organic molecules.

The word also applies outside biology. Chemical decomposition can split a compound into simpler substances—for example, water can be separated into hydrogen and oxygen under suitable conditions. Physical decomposition may describe an object being divided into parts without changing the substances involved.

A common mix-up is “decay,” which usually refers specifically to the gradual breakdown of dead organic matter. Decomposition is broader and can include biological, chemical, or physical breakdown.