Hello Prashant,

There are two types of solids:

1. Crystalline solids
2. Amorphous solids

So basically, amorphous solid is the type of solid which does not have a definite geometrical shape or size unlike crystals. By this, I mean that the atoms are not arranged in a pattern. Examples include glass, plastic and gel.

In condensed matter physics and materials science, an amorphous or non-crystalline solid is a solid that lacks the long-range order that is characteristic of a crystal or An amorphous solid is any noncrystalline solid in which the atoms and molecules are not organized in a definite lattice pattern. Such solids include glass, plastic, and gel.