What are materials, exactly?

That's a big question - because materials are the basic substances that make up, well, you name it! Materials can be natural - like wood, or human-made - like plastic. There are now about 300,000 different known materials (if you named one every second, it would take you more than three whole days and nights just to get through the list!). And as materials scientists create and combine materials in new ways, the number's almost infinite.

Most materials fit into a few big, general categories:

Metals
Whole periods of human civilization - such as the Bronze and Iron ages - are named for metals. These were the first materials to be "engineered," that is, people changed them to fit what they needed to do, rather than just letting their natural properties determine what they could be used for. These days, materials scientists are using metals in ways no one could have pictured even a few years ago - for example, shaping copper into tiny wires a thousand times skinnier than a strand of your hair!

Ceramics
Think about a china teapot - that's one type of ceramic. But ceramics can also be used to create bone and tooth replacements, super-strong cutting tools, or to conduct electricity. With the addition of oxygen or nitrogen, metals become ceramics, too.

Semiconductors
One of these materials - silicon - is making it possible for you to read these words right now! That's because silicon is the essential material in an electronic computer chip. "Semiconductor" means a material can conduct electricity with a bit of help in the form of added "impurities." Your CD, DVD player, and telephone - all depend on semiconductors.

Polymers
Polymers are just very big molecules made of smaller molecules linked together into long, repeating chains. You may not know it, but you're in touch with polymers every day more than any other kind of material. Rubber bands are made of polymers, so are paints and every kind of plastic. And by the way, most of the food you eat is made of natural polymers!

Others are little tougher to define...

Composites
Composites are combinations of materials, which can be as simple as concrete reinforced with steel bars or as leading edge as an ultralight, carbon-fiber bicycle. The places where different materials meet - the "interfaces" - often produce new properties that are radically different, and better, than those in any single material.

Biomaterials
Every part of your body is a material! Bone, muscles, fingernails, hair, and skin are all examples of different types of materials found in your body with remarkable properties that help you survive - from keeping you upright, and protecting you from heat or cold, to cutting and grinding your food. Some scientists try to mimic nature's designs to create materials for other uses, such as using the foam structure of bone as an inspiration for designing materials that are lightweight and strong.

And some are just plain weird...

Exotic and Strange Materials
Materials scientists are discovering and creating entirely new types of materials - such as buckyballs and nanotubes, which are very tiny spheres or cylinders made of carbon atoms. Then there are aerogels, which are extremely lightweight porous materials made almost entirely of air! Nanotechnology is taking materials science into a new dimension, as scientists create new materials atom-by-atom and molecule-by-molecule - leading to properties and performance never before imagined.

Who are materials scientists and what do they do?

You've probably heard of a chemist, a biologist or a physicist, but have you ever heard of a materials scientist? Probably not. One reason is that materials science covers a huge range of activity and touches on many different fields - including chemistry, biology and physics! Sometimes materials scientists are called ceramic or polymer engineers or metallurgists, and you can find them working in industries, labs, and universities all over the world.

But diverse as they are, materials scientists look at materials from a unified point of view: they look for connections between the underlying structure of a material, its properties, how processing changes it, and what the material can do - its performance.

In the past, people used and changed materials by trial and error. And they worked on a big, visible scale - for example, heating then rapidly cooling chunks of iron to make it harder. Modern materials scientists manipulate and change materials based on fundamental understandings of how the materials are put together, often on the invisibly-tiny scale of atoms. How small is that? To make a speck as big as the period at the end of this sentence, you'd need trillions of atoms.

How can I find out more?

For a deeper understanding of materials science, explore these web links, books and videos.

For a window into the association that joins together materials scientists from around the world, visit the Materials Research Society.

News! The latest in materials science

A great source for news of the amazing discoveries and innovations in materials science is the Materials Research Society's Research News and Features Bulletin.

Note: the descriptions of the research can get pretty technical! Your teacher or parents can help you sort it out.