Liquids are one of the four common states of matter - the others are solids, gases, and plasmas. In general, but not in all specific cases, as the temperature increases and pressure decreases substances pass through the four different states.
The liquid state of matter is characterized by the following properties:
- its volume is fixed; it will not expand to fill a container - unlike gases and plasmas
- most liquids are incompressible - their volume hardly changes when pressure changes - unlike gases and plasmas
- liquids are fluids, so they can flow. Provided there is gravity, their shapes adapt to that of their containers - unlike solids
- liquids are condensed matter, so their volumes are similar to those of solids, and much smaller than gases and plasmas
Definition for liquid crystal: A substance that has liquid-like long-range disorder but some crystal-like aspects of short-range order.