Six categories that encompass the materials
available to practicing engineers :
1). Metals (crystalline materials, metallic bonding)
2). Ceramics (crystalline materials, ionic bonding)
3). Glasses (mainly non-crystalline materials, ionic bond)
4). Polymers (non-crystalline materials, covalent
bonding)
5). Composites(mixture of above materials)
6). Semiconductors (unique electrical conducting
behavior)