The most commonly referred to states of matter are solid, liquid, gas and plasma.
These ‘phases’ or ‘states’ see solids with closely-packed atoms in rigid arrangements.
Heating these atoms provides energy that allows them to vibrate and shake apart, forming liquids that can flow and adopt shape.
Continuing to heat these atoms loosens bonding further and allows atoms to spread out at great speed in all directions as a gas.
At greater temperatures still, electrons can be knocked out of the atoms grasp to form an electrically charged, ionised plasma, the effects of which you can see in ‘plasma balls’ or in pictures of the corona of the Sun.
Below is a short video of a plasma disk at Glasgow Science Centre – very cool!