The matter is such a physical entity that has mass and occupies space. This word is used to cover all the substances and materials from which the physical universe is composed. Usually, all matters can exist in three different states- solid, liquid and gaseous states. For example- water (liquid) can exist as ice (solid) or water vapour (gas).

These are what we call the three states of matter.

Solid

A solid, at a particular temperature, has a fixed shape and volume which may be affected by changes in temperature. Solids usually increase slightly in size when it is heated (expansion) and usually decrease in size if it is cooled (contraction).

 

Liquid

A liquid, at a particular temperature, has a  fixed volume and will take up the shape of any container into which it is poured. Like a solid, its volume is slightly affected by changes in temperature.

 

Gas

A gas, at a particular temperature, has neither a definite shape nor a definite volume. It takes up the shape of any container into which it is placed and will spread out evenly within it. It is much lighter than the same volume of solid or liquid.

Unlike those of solids and liquids, the volumes of gases are quite markedly affected by changes in temperature. Unlike solid, liquid and gases are relatively compressible. So, their volume can be reduced by the application of pressure. Gases are much more compressible than liquids.