Structure is a fundamental concept in science. It means the arrangement of parts. Examples are the organs in a body, or crystals in a substance like granite.
A structure may refer to buildings, machines and similar things made by people as well as to a rock or a mineral, atoms or sentences. It always reflects the hierarchy of its parts.
A traditional Sami food storage structure
Gothic quadripartite cross-ribbed vaults of the Saint-Séverin church in Paris
Ribbon schematic of the 3D structure of the protein triosephosphate isomerase. The brown spirals are α-helices and the green arrows are β strands, the components of β-pleated sheets.