Before we discuss ceramics and their structures it may be useful for you to review theory on atomic bonding.
Ceramic and glass atomic structures are a network of either ionic or covalent bonds. Quite often they are a mixture of both. The individual structures are quite complex, so we will look briefly at the basic features in order that you can better understand their material properties.
Most ceramics have ionic bonding which leads to very high strength. These ceramics are typically a combination of a metal and a non-metal, e.g. sodium chloride NaCl or alumina Al2O3.
Some ceramics, however, have covalent bonding. These are either a combination of two non-metals, e.g. silica SiO2, or pure elements, e.g. diamond C.