States of matter in physics are the distinct forms that different phases of matter take on. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma. Further states are possible but do not naturally occur in our environment: BoseEinstein condensates, neutron stars. Other states, such as quark-gluon plasmas, are believed to be possible.
Solids are substances which have a definite shape and volume
Because of its complexity and lack of knowledge and resources.