Ceramic products can be crudely categorised as whiteware, refractory or engineering - generally a function of their end-use.
Whitewares (e.g. dinner plates, etc) are familiar to the vast majority of us; refractories are used in applications such as furnace linings and crucibles. Engineering ceramics are used in 'high-tech' applications such as aerospace, electronics and biomedical. All ceramics are made from the same basic ingredients, i.e. carbon, nitrogen, oxygen, or boron in combination with a metal, e.g. aluminium or silicon. They combine in relatively simple combinations Al2O3 , SiO2 , for example. In nature, these materials are found in abundance, but they usually contain impurities - another oxide for example.
Engineering ceramics - also referred to as advanced, structural or fine ceramics - have been processed to be very pure and, in general, have superior properties to unrefined ceramics. Many are man-made, i.e. they do not occur naturally, e.g. silicon nitride, and their properties can be enhanced to produce very high strength at high temperatures, good corrosion resistance, etc.