From Academic Kids
A solid is a state of matter, characterized by a definite volume and a definite shape (i.e. it resists deformation). Within a solid, atoms/molecules are relatively close together, or "rigid"; however, this does not prevent the solid from becoming deformed or compressed. In the solid phase of matter, atoms have a fixed spatial ordering; because all matter has some kinetic energy, the atoms in even the most rigid solid move slightly, but this movement is "invisible".
Solid state chemistry overlaps both of these fields, but is especially concerned with the synthesis of novel materials.