State of matterIn physics, a state of matter is one of the distinct forms that matter takes on. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma. Many other states are known, such as Bose!instein condensates and neutron"degenerate matter, but these only occur in e#treme situations such as ultra cold or ultra dense matter. $ther states, such as quarkgluon plasmas, are believed to be possible but remain theoretical for now. For a complete list of all e#otic states of matter, see the list of states of matter.%istorically, the distinction is made based on qualitative differences in properties. Matter in the solid state maintains a fi#ed volume and shape, with component particles &atoms, molecules or ions' close together and fi#ed into place. Matter in the liquid state maintains a fi#ed volume, but has a variable shape that adapts to fit its container. Its particles are still close together but move freely. Matter in the gaseous state has both variable volume and shape, adapting both to fit its container. Itsparticles are neither close together nor fi#ed in place. Matter in the plasma state has variable volumeand shape, but as well as neutral atoms, it contains a significant number of ions and electrons, both of which can move around freely. (lasma is the most common form of visible matter in the universe.)*he four fundamental states of matter. +lockwise from top left, they are solid, liquid, plasma, and gas, represented by an ice sculpture, a drop of water, electrical arcingfrom a tesla coil, and the air around clouds, respectively.*he term phase is sometimes used as a synonym for state of matter, but a system can contain several immiscible phases of the same state of matter &see (hase &matter' for more discussion of the difference between the two terms'.