Crystalline Solids: Solid with a well-defined/ordered structures of repeated units
        vs.
Amorphous Solids: Solid with a dis-ordered structure
 

Crystal Lattice: A regular repeated arrangement of points in space consisting of unit cells

Unit Cell:          The smallest box-like unit from which one can construct a crystal
                                 by stacking them.
 

LATTICE SYSTEM

       5 Different Basic Types exists in 2 Dimensions

       7 Different Basic Types exists in 3 Dimensions

Please refer to the Figures