Solids are a type of matter that hold their constituent particles tightly packed by using strong intermolecular forces and short internuclear distance. At low temperatures, the solid particles oscillate at their mean positions, and remain fixed in one position, to attain a definite shape and volume.
Solids can expand and contract with changes in temperature. Usually, the density of a solid is listed along with the temperature at which its density was determined. A true solid possesses a crystalline structure, where particles are arranged in an ordered and three-dimensional pattern. Solids are characterized as rigid and incompressible, with high densities.