What are non-crystalline?

Crystals are type of solid state bodies whose structural order are well defined and have a unique lattice structures. There is a perfect distance between the various layers in its structure. Crystallinity has big influence on the hardness, density of the body. Non- Crystalline substances are the ones who lack the structural order and do not posses the well defined lattice structure. They tend to have lower density and low melting point as there atoms are scattered. Crystals have high tensile strength while the non crystals are not.