Mankind relies on materials because of the advantages gained by modifying their characteristics. The ability to conduct electricity, to be magnetized, to allow light to pass through, to withstand force, and to be robust are all examples of such characteristics. It is the atomic and molecular structures inside the materials themselves that are responsible for all of these characteristics. The atomic make-up of a material, its local atomic configuration, and the way these atomic arrangements are arranged to form microstructures are all examples of structural characteristics. Metals, composites, polymers, ceramics, semiconductors, bio-materials, and nano-materials are just a few examples of the many different types of materials that exist. The study of materials encompasses several subfields and so may be categorized as an interdisciplinary study. Materials science include the investigation of existing materials, the development of novel materials, and the modification of existing materials to better fit certain uses.