Those three states are the bread and butter of any school child, but it's, unfortunately, a woefully incomplete list. In everyday life, we can observe four states of matter pretty easily, the three listed above and plasma (that's the stuff the sun is made of, remember?). Then we have a list as long as your arm of a load of other states of matter that don't quite fit into those four categories. These include, but are not limited to, superfluids, supersolids, liquid crystals, dark matter and whatever the hell glass is made of (seriously, we still haven't managed to agree on that one, it's currently classed as an amorphous solid). There are some more everyday examples that you probably have in your house. Shaving foam (or whipped cream or whatever) is made up of a liquid and a gas, but has many of the properties of a solid. A magnetically ordered state is also considered a non-classical state of matter, so those fridge magnets are breaking the rules too.
